Line 1: |
Line 1: |
− | <pre>
| + | A simple observation: the first accessory any computer user |
| + | should buy is hard drive. On a dollar for dollar basis nothing |
| + | speeds up processing and expands convenience like a hard drive. |
| + | The bad news? The substantial storage capacity of a hard drive |
| + | contains the seeds of data catastrophe if you don't understand |
| + | how to CAREFULLY maintain a hard drive. Some reference |
| + | information pertaining to larger desktop hard drives as well as |
| + | smaller laptop drives has been retained since drives in both |
| + | computers are similar in function although different in form and |
| + | size. |
| | | |
− | ----------------------------------------------------------------
| + | Many computer operations tend to slow down at the critical |
− |
| + | bottleneck of information transfer from computer memory (RAM) to |
− | HARD DISKS - THE ESSENTIAL ACCESSORY
| + | disk. The faster the transfer, the faster the program operates. |
| + | Nine times out of ten it is the bottleneck formed when |
| + | information flows to or from a disk that you and your program |
| + | must wait. This is where a hard drive really shines - speed. |
| | | |
− | ----------------------------------------------------------------
| + | Given the best possible treatment, a hard drive should last from |
| + | eight to fifteen years. Drive manufacturers typically suggest |
| + | 30,000 to 70,000 hours of routine life for a hard drive before |
| + | failure. If you kept your PC on for a 40 hour work week for 50 |
| + | weeks - you could expect about 15 years of service for a drive |
| + | rated at 30,000 hours. Some hard drive users even suggest |
| + | leaving the drive on continuously or alternatively turning it on |
| + | in the morning and off at night to minimize motor and bearing |
| + | wear since it is the starting shock which wears most heavily on |
| + | a drive. However, given marginal treatment or abuse, you can |
| + | expect about fifteen minutes of service followed by a $250 |
| + | repair bill. Obviously a little information about hard drives |
| + | and their care can't hurt. |
| | | |
− | A simple observation: the first accessory any computer user
| + | |
− | should buy is hard drive. On a dollar for dollar basis nothing
| |
− | speeds up processing and expands convenience like a hard drive.
| |
− | The bad news? The substantial storage capacity of a hard drive
| |
− | contains the seeds of data catastrophe if you don't understand
| |
− | how to CAREFULLY maintain a hard drive. Some reference
| |
− | information pertaining to larger desktop hard drives as well as
| |
− | smaller laptop drives has been retained since drives in both
| |
− | computers are similar in function although different in form and
| |
− | size.
| |
− | | |
− | Many computer operations tend to slow down at the critical
| |
− | bottleneck of information transfer from computer memory (RAM) to
| |
− | disk. The faster the transfer, the faster the program operates.
| |
− | Nine times out of ten it is the bottleneck formed when
| |
− | information flows to or from a disk that you and your program
| |
− | must wait. This is where a hard drive really shines - speed.
| |
| | | |
− | Given the best possible treatment, a hard drive should last from
| + | TECHNOLOGY 101 - BOOT CAMP FOR HARD DRIVE USERS |
− | eight to fifteen years. Drive manufacturers typically suggest
| |
− | 30,000 to 70,000 hours of routine life for a hard drive before
| |
− | failure. If you kept your PC on for a 40 hour work week for 50
| |
− | weeks - you could expect about 15 years of service for a drive
| |
− | rated at 30,000 hours. Some hard drive users even suggest
| |
− | leaving the drive on continuously or alternatively turning it on
| |
− | in the morning and off at night to minimize motor and bearing
| |
− | wear since it is the starting shock which wears most heavily on
| |
− | a drive. However, given marginal treatment or abuse, you can
| |
− | expect about fifteen minutes of service followed by a $250
| |
− | repair bill. Obviously a little information about hard drives
| |
− | and their care can't hurt.
| |
| | | |
− | ----------------------------------------------------------------
| |
− |
| |
− | TECHNOLOGY 101 - BOOT CAMP FOR HARD DRIVE USERS
| |
| | | |
− | ----------------------------------------------------------------
| + | What is a hard drive? If you have worked with a floppy disk you |
| + | already understand something about hard drives. Basically the |
| + | hard drive unit is a sealed chamber (sealed against dust and |
| + | dirt) which contains rapidly spinning single or multiple stacked |
| + | platters. The platter(s) are similar to a floppy disk in that |
| + | they store information magnetically - data can be erased and |
| + | rewritten as needed. The trick is, however, that the storage |
| + | capability is immense on a hard drive. |
| | | |
− | What is a hard drive? If you have worked with a floppy disk you
| + | A floppy typically holds about one third of a million computer |
− | already understand something about hard drives. Basically the
| + | characters (360,000 or 360K bytes). The hard drive can commonly |
− | hard drive unit is a sealed chamber (sealed against dust and
| + | hold 20 to 40 million (or more!) bytes or computer words. In |
− | dirt) which contains rapidly spinning single or multiple stacked
| + | addition, the hard drive motor spins the magnetic platter |
− | platters. The platter(s) are similar to a floppy disk in that
| + | quickly so that information is transferred rapidly rather than |
− | they store information magnetically - data can be erased and
| + | the tedious rate of the leisurely spinning floppy. A small |
− | rewritten as needed. The trick is, however, that the storage
| + | read/write head hovers and moves above the hard drive magnetic |
− | capability is immense on a hard drive.
| + | platter much like a phonograph needle above a record. The |
| + | difference is that the read/write head of the hard drive rides |
| + | slightly above the platter on a thin cushion of air. In the |
| + | floppy drive mechanism, the read/write head is in direct contact |
| + | with the floppy. All hard drives are installed in two parts: the |
| + | drive (a box containing the disk and read/write head) and the |
| + | controller (a circuit board) which may be integrated into the |
| + | drive or a separate circuit board. The hard drive stores the |
| + | information. The controller assumes the role of a high speed |
| + | "translator/traffic cop" to help the hard drive move its massive |
| + | amount of information smoothly. |
| | | |
− | A floppy typically holds about one third of a million computer
| + | Back to the magnetic platter for a moment. The read write heads |
− | characters (360,000 or 360K bytes). The hard drive can commonly
| + | are mounted on a moveable arm and each position of the head |
− | hold 20 to 40 million (or more!) bytes or computer words. In
| + | above the platter defines a circular TRACK just like the track |
− | addition, the hard drive motor spins the magnetic platter
| + | of a phonograph record. As the arm changes positions, different |
− | quickly so that information is transferred rapidly rather than
| + | circular tracks are traced magnetically upon the surface of the |
− | the tedious rate of the leisurely spinning floppy. A small
| + | platter. Most hard drives have several read/write heads which |
− | read/write head hovers and moves above the hard drive magnetic
| + | service both the top and bottom of each platter. A set of tracks |
− | platter much like a phonograph needle above a record. The
| + | on different platters define a vertical CYLINDER somewhat like |
− | difference is that the read/write head of the hard drive rides
| + | the surface of a tin can whose top and bottom are missing. Large |
− | slightly above the platter on a thin cushion of air. In the
| + | hard drives can have six or more platters and therefore 12 or |
− | floppy drive mechanism, the read/write head is in direct contact
| + | more sides for information storage. The tracks can also be |
− | with the floppy. All hard drives are installed in two parts: the
| + | defined as divisions of equally divided data called SECTORS |
− | drive (a box containing the disk and read/write head) and the
| + | which are something like portions of the outer edge of a circle. |
− | controller (a circuit board) which may be integrated into the
| + | Finally, the sum collection of tracks, sectors and cylinders |
− | drive or a separate circuit board. The hard drive stores the
| + | define the entire VOLUME of the hard disk. |
− | information. The controller assumes the role of a high speed
| |
− | "translator/traffic cop" to help the hard drive move its massive
| |
− | amount of information smoothly.
| |
| | | |
− | Back to the magnetic platter for a moment. The read write heads
| + | Each piece of data has an address which tells the read/write |
− | are mounted on a moveable arm and each position of the head
| + | heads where to move to locate that specific piece of |
− | above the platter defines a circular TRACK just like the track
| + | information. If you tell the read/write heads to move to and |
− | of a phonograph record. As the arm changes positions, different
| + | hover over a specific track, sooner or later your data will pass |
− | circular tracks are traced magnetically upon the surface of the
| + | beneath it. Since you can move the heads directly to a given |
− | platter. Most hard drives have several read/write heads which
| + | track quickly, the early nomenclature for a hard drive was the |
− | service both the top and bottom of each platter. A set of tracks
| + | DASD or DIRECT ACCESS STORAGE DEVICE. |
− | on different platters define a vertical CYLINDER somewhat like
| |
− | the surface of a tin can whose top and bottom are missing. Large
| |
− | hard drives can have six or more platters and therefore 12 or
| |
− | more sides for information storage. The tracks can also be
| |
− | defined as divisions of equally divided data called SECTORS
| |
− | which are something like portions of the outer edge of a circle.
| |
− | Finally, the sum collection of tracks, sectors and cylinders
| |
− | define the entire VOLUME of the hard disk.
| |
| | | |
− | Each piece of data has an address which tells the read/write
| + | Movement of the read/write head arm takes a little time. For |
− | heads where to move to locate that specific piece of
| + | this reason an ACCESS TIME is associated with hard drives and |
− | information. If you tell the read/write heads to move to and
| + | stated in advertising and specification sheets. Generally this |
− | hover over a specific track, sooner or later your data will pass
| + | time is stated as the AVERAGE ACCESS TIME and is frequently in |
− | beneath it. Since you can move the heads directly to a given
| + | the thousandths of seconds or millisecond range which is fast |
− | track quickly, the early nomenclature for a hard drive was the
| + | indeed. The old IBM XT class machines featured access times |
− | DASD or DIRECT ACCESS STORAGE DEVICE.
| + | around 85 milliseconds with the AT class machines featuring |
| + | access times around 40 seconds. Newer hard drives post times in |
| + | the 28 to 15 millisecond access range. Remember, the faster you |
| + | can move the read/write heads, the faster you can get to your |
| + | data. |
| | | |
− | Movement of the read/write head arm takes a little time. For
| + | The AVERAGE WAIT TIME is a less frequently discussed number but |
− | this reason an ACCESS TIME is associated with hard drives and
| + | equally interesting. Once the read/write head is positioned over |
− | stated in advertising and specification sheets. Generally this
| + | the track holding your data, the system must wait for the |
− | time is stated as the AVERAGE ACCESS TIME and is frequently in
| + | correct sector to pass beneath. Obviously, the average wait time |
− | the thousandths of seconds or millisecond range which is fast
| + | is one half the time it takes for a full rotation of the |
− | indeed. The old IBM XT class machines featured access times
| + | platter. This figure is rarely given in advertisements and is |
− | around 85 milliseconds with the AT class machines featuring
| + | usually comparable for most drives of the same type and is |
− | access times around 40 seconds. Newer hard drives post times in
| + | generally much shorter than the access time. Speed matters to a |
− | the 28 to 15 millisecond access range. Remember, the faster you
| + | hard drive! Average wait time is published if you dig it out of |
− | can move the read/write heads, the faster you can get to your
| + | the specification sheet or write to the manufacturer. |
− | data.
| |
| | | |
− | The AVERAGE WAIT TIME is a less frequently discussed number but
| + | An extension of this logic brings us to consider the INTERLEAVE |
− | equally interesting. Once the read/write head is positioned over
| + | FACTOR for a disk. Generally a hard drive reads and writes |
− | the track holding your data, the system must wait for the
| + | information in sectors of the same, repeatable size such as 512 |
− | correct sector to pass beneath. Obviously, the average wait time
| + | bytes. However programs and data files are usually much bigger |
− | is one half the time it takes for a full rotation of the
| + | than this and obviously must be scattered onto many sectors. The |
− | platter. This figure is rarely given in advertisements and is
| + | problem is that the disk rotation is much too fast for a large |
− | usually comparable for most drives of the same type and is
| + | file to be written in perfectly contiguous sectors on the same |
− | generally much shorter than the access time. Speed matters to a
| + | track. If you tried to write the data onto a track, one byte |
− | hard drive! Average wait time is published if you dig it out of
| + | after the next, the central processing unit chip or CPU could |
− | the specification sheet or write to the manufacturer.
| + | not absorb the data fast enough. |
| | | |
− | An extension of this logic brings us to consider the INTERLEAVE
| + | The solution is to place sectors to be read in ALTERNATING |
− | FACTOR for a disk. Generally a hard drive reads and writes
| + | fashion which gives the CPU time to digest the data. Thus if a |
− | information in sectors of the same, repeatable size such as 512
| + | circular track on the platter had 8 sectors you might number and |
− | bytes. However programs and data files are usually much bigger
| + | read them in this order: 1,5,2,6,3,7,4,8. This way the CPU has a |
− | than this and obviously must be scattered onto many sectors. The
| + | "breather" in between each sector read. The number of rotations |
− | problem is that the disk rotation is much too fast for a large
| + | it takes the heads to read ALL tracks in succession is the |
− | file to be written in perfectly contiguous sectors on the same
| + | INTERLEAVE FACTOR. Slow CPU chips can force a disk to use an |
− | track. If you tried to write the data onto a track, one byte
| + | interleave factor of 3 or even 4. A faster processor might be |
− | after the next, the central processing unit chip or CPU could
| + | able to handle a disk interleave of 1:2 (such as 80286 processor |
− | not absorb the data fast enough.
| + | chips) or even 1:1 (such as 80386 processor chips.) It is |
| + | possible to low level format a disk and change its interleave |
| + | factor; but if the CPU cannot keep up, the adjustment is |
| + | worthless. To the processor operating in millionths of a second, |
| + | the time drain of waiting for a hard drive which operates in |
| + | thousandths of a second or floppy drive which operates in tenths |
| + | and full seconds is wasted time. The obvious point of logic is |
| + | that when using a hard drive you need to organize files for |
| + | minimum time delays for the processor. |
| | | |
− | The solution is to place sectors to be read in ALTERNATING
| + | The first outer track on a disk is always the boot record which |
− | fashion which gives the CPU time to digest the data. Thus if a
| + | loads the main portions of DOS into the machine. Following this |
− | circular track on the platter had 8 sectors you might number and
| + | is the file allocation table or FAT which we discussed in |
− | read them in this order: 1,5,2,6,3,7,4,8. This way the CPU has a
| + | earlier tutorials. The FAT maintains data in CLUSTERS which, for |
− | "breather" in between each sector read. The number of rotations
| + | an XT class machine are 4096 bytes. On the AT class machine the |
− | it takes the heads to read ALL tracks in succession is the
| + | cluster size is 2048 bytes which is much more efficient and less |
− | INTERLEAVE FACTOR. Slow CPU chips can force a disk to use an
| + | wasteful of disk space. Following the FAT are the sectors for |
− | interleave factor of 3 or even 4. A faster processor might be
| + | the root directory of the hard drive. Each directory entry is 32 |
− | able to handle a disk interleave of 1:2 (such as 80286 processor
| + | bytes in length. Curiously, and to our good advantage, unused |
− | chips) or even 1:1 (such as 80386 processor chips.) It is
| + | entries in the directory have a unique first character byte. |
− | possible to low level format a disk and change its interleave
| + | When a file is deleted though DOS, ONLY the first character is |
− | factor; but if the CPU cannot keep up, the adjustment is
| + | reset. |
− | worthless. To the processor operating in millionths of a second,
| |
− | the time drain of waiting for a hard drive which operates in
| |
− | thousandths of a second or floppy drive which operates in tenths
| |
− | and full seconds is wasted time. The obvious point of logic is
| |
− | that when using a hard drive you need to organize files for
| |
− | minimum time delays for the processor.
| |
| | | |
− | The first outer track on a disk is always the boot record which
| + | Fortunately this allows various utility programs to attempt to |
− | loads the main portions of DOS into the machine. Following this
| + | recover the deleted file since ONLY the directory data is |
− | is the file allocation table or FAT which we discussed in
| + | altered but NOT the file itself. However, as time goes on and |
− | earlier tutorials. The FAT maintains data in CLUSTERS which, for
| + | additional files are added to the disk, the original file is |
− | an XT class machine are 4096 bytes. On the AT class machine the
| + | overwritten by new information. This is why you need to act |
− | cluster size is 2048 bytes which is much more efficient and less
| + | immediately if you discover you have accidentally deleted a |
− | wasteful of disk space. Following the FAT are the sectors for
| + | file. An advantage to the use of the FAT is that files do not |
− | the root directory of the hard drive. Each directory entry is 32
| + | have to be given a fixed amount of space on a disk - they can |
− | bytes in length. Curiously, and to our good advantage, unused
| + | use as many or few clusters as needed. The downside is that the |
− | entries in the directory have a unique first character byte.
| + | file pieces can be scattered wildly over the surface of the disk |
− | When a file is deleted though DOS, ONLY the first character is
| + | in a non contiguous fashion which only the FAT can track. This |
− | reset.
| + | means more read/write head motion and more wasted time as far as |
| + | the CPU and the performance of your program is concerned. |
| | | |
− | Fortunately this allows various utility programs to attempt to
| + | Additionally, if you have many deleted files within the |
− | recover the deleted file since ONLY the directory data is
| + | directory, DOS must search tediously through each one from top |
− | altered but NOT the file itself. However, as time goes on and
| + | to bottom of the directory to find a match for the file you are |
− | additional files are added to the disk, the original file is
| + | trying to locate. Obviously, then, programs and data of high use |
− | overwritten by new information. This is why you need to act
| + | should have their directory entries located near the top of the |
− | immediately if you discover you have accidentally deleted a
| + | directory to speed the search. Each time the read/write head |
− | file. An advantage to the use of the FAT is that files do not
| + | moves takes time: searching the directory and finding the pieces |
− | have to be given a fixed amount of space on a disk - they can
| + | of the scattered file all take movement of the read/write arm. |
− | use as many or few clusters as needed. The downside is that the
| + | There are several ways to unfragment files which boost disk |
− | file pieces can be scattered wildly over the surface of the disk
| + | performance, and we'll talk about those techniques it a bit. |
− | in a non contiguous fashion which only the FAT can track. This
| |
− | means more read/write head motion and more wasted time as far as
| |
− | the CPU and the performance of your program is concerned.
| |
| | | |
− | Additionally, if you have many deleted files within the
| |
− | directory, DOS must search tediously through each one from top
| |
− | to bottom of the directory to find a match for the file you are
| |
− | trying to locate. Obviously, then, programs and data of high use
| |
− | should have their directory entries located near the top of the
| |
− | directory to speed the search. Each time the read/write head
| |
− | moves takes time: searching the directory and finding the pieces
| |
− | of the scattered file all take movement of the read/write arm.
| |
− | There are several ways to unfragment files which boost disk
| |
− | performance, and we'll talk about those techniques it a bit.
| |
| | | |
− | ----------------------------------------------------------------
| |
| | | |
− | HARD DISKS - STRATEGIES FOR TURBOCHARGED RESULTS
| |
| | | |
− | ----------------------------------------------------------------
| + | HARD DISKS - STRATEGIES FOR TURBOCHARGED RESULTS |
| | | |
− | Before we examine methods for improving hard drive performance,
| |
− | several simple "care and feeding" precautions should be
| |
− | mentioned.
| |
| | | |
− | Hard drives are touchy if mistreated! Once brought up to speed,
| + | Before we examine methods for improving hard drive performance, |
− | a hard drive should never be bumped or moved. The read/write
| + | several simple "care and feeding" precautions should be |
− | head (similar to the phonograph needle resting on a record) will
| + | mentioned. |
− | smash or chip into the surface of the spinning hard drive
| + | |
− | platter and take your data with it. Either the head or the
| + | Hard drives are touchy if mistreated! Once brought up to speed, |
− | magnetically coated platter can be permanently damaged. Allow
| + | a hard drive should never be bumped or moved. The read/write |
− | the hard drive to some to a complete stop before moving the
| + | head (similar to the phonograph needle resting on a record) will |
− | computer.
| + | smash or chip into the surface of the spinning hard drive |
| + | platter and take your data with it. Either the head or the |
| + | magnetically coated platter can be permanently damaged. Allow |
| + | the hard drive to some to a complete stop before moving the |
| + | computer. |
| | | |
− | In addition always use a "parking" software package to move the
| + | In addition always use a "parking" software package to move the |
− | read/write head to the safety zone before turning off the
| + | read/write head to the safety zone before turning off the |
− | computer. A parking program usually accompanies most computers
| + | computer. A parking program usually accompanies most computers |
− | which have hard drives installed or can be obtained from
| + | which have hard drives installed or can be obtained from |
− | commercial or shareware sources. A few drives automatically park
| + | commercial or shareware sources. A few drives automatically park |
− | the heads when turned off but this tends to be a rare feature
| + | the heads when turned off but this tends to be a rare feature |
− | seen mostly on high priced hard drives.
| + | seen mostly on high priced hard drives. |
| | | |
− | Always maintain copies of data and programs outside the hard
| + | Always maintain copies of data and programs outside the hard |
− | drive by "backing up" onto a floppy or tape. How often should
| + | drive by "backing up" onto a floppy or tape. How often should |
− | you back up your files? Daily if you use the computer to produce
| + | you back up your files? Daily if you use the computer to produce |
− | many changes to important documents. Weekly backup is probably a
| + | many changes to important documents. Weekly backup is probably a |
− | bare minimum considered reasonable for occasional computer
| + | bare minimum considered reasonable for occasional computer |
− | users. Other computer users maintain vital data on floppies or
| + | users. Other computer users maintain vital data on floppies or |
− | other backup systems and use the hard drive to store programs or
| + | other backup systems and use the hard drive to store programs or |
− | applications only such as a spreadsheet or database. Backups are
| + | applications only such as a spreadsheet or database. Backups are |
− | a good idea even for floppy disk systems which have no hard
| + | a good idea even for floppy disk systems which have no hard |
− | drive.
| + | drive. |
| | | |
− | Make two copies of every file regardless of whether you have a
| + | Make two copies of every file regardless of whether you have a |
− | hard drive or not. Some shareware and commercial utilities ease
| + | hard drive or not. Some shareware and commercial utilities ease |
− | the backup chore by only copying those files to a floppy which
| + | the backup chore by only copying those files to a floppy which |
− | have been changed or updated since the last backup has been
| + | have been changed or updated since the last backup has been |
− | performed. They ignore files which have not changed and thus do
| + | performed. They ignore files which have not changed and thus do |
− | not require copying again. This can save a lot of time when
| + | not require copying again. This can save a lot of time when |
− | backing up valuable files from your hard drive to a floppy for
| + | backing up valuable files from your hard drive to a floppy for |
− | safekeeping.
| + | safekeeping. |
| | | |
− | Hard drives should periodically be reorganized (files
| + | Hard drives should periodically be reorganized (files |
− | unfragmented) to ensure speedy retrieval and access to data.
| + | unfragmented) to ensure speedy retrieval and access to data. |
− | Inexpensive or free software programs known as "disk file
| + | Inexpensive or free software programs known as "disk file |
− | unfragmenters" do this job nicely. As disk files are created and
| + | unfragmenters" do this job nicely. As disk files are created and |
− | deleted, blank spaces and unused sectors begin to build up.
| + | deleted, blank spaces and unused sectors begin to build up. |
| | | |
− | Gradually files are broken into pieces and scattered over the
| + | Gradually files are broken into pieces and scattered over the |
− | many tracks and sectors of the disk. This happens to both
| + | many tracks and sectors of the disk. This happens to both |
− | floppies and hard drives, but is especially annoying on hard
| + | floppies and hard drives, but is especially annoying on hard |
− | drives because of the dramatic increase in time it takes to load
| + | drives because of the dramatic increase in time it takes to load |
− | a program or data file. The File allocation table is the
| + | a program or data file. The File allocation table is the |
− | culprit, sense all data is packed away in the first and handiest
| + | culprit, sense all data is packed away in the first and handiest |
− | sector on the drive which the FAT can find.
| + | sector on the drive which the FAT can find. |
| | | |
− | The FAT allows files to be fragmented down to the cluster level.
| + | The FAT allows files to be fragmented down to the cluster level. |
− | One way to unfragment a disk is to copy all of the files off to
| + | One way to unfragment a disk is to copy all of the files off to |
− | floppies and then recopy them back to the hard drive - a tedious
| + | floppies and then recopy them back to the hard drive - a tedious |
− | nuisance at best. You would do this with the DOS XCOPY or COPY
| + | nuisance at best. You would do this with the DOS XCOPY or COPY |
− | commands but not DISKCOPY since this would retain the tracks and
| + | commands but not DISKCOPY since this would retain the tracks and |
− | their fragmentation as you first found them.
| + | their fragmentation as you first found them. |
| | | |
− | Defragmenting programs perform this task without requiring
| + | Defragmenting programs perform this task without requiring |
− | removal of the files from the hard drive. They perform their
| + | removal of the files from the hard drive. They perform their |
− | magic by moving around the clusters of a scattered file in such
| + | magic by moving around the clusters of a scattered file in such |
− | a way as to reassemble it into contiguous pieces again. Some
| + | a way as to reassemble it into contiguous pieces again. Some |
− | customization is permitted with the more sophisticated
| + | customization is permitted with the more sophisticated |
− | "defragmenting" programs. For example, subdirectory files can be
| + | "defragmenting" programs. For example, subdirectory files can be |
− | relocated after the root or below a different subdirectory or,
| + | relocated after the root or below a different subdirectory or, |
− | in another example, high use files might be placed higher in the
| + | in another example, high use files might be placed higher in the |
− | directory listing for faster disk access.
| + | directory listing for faster disk access. |
| | | |
− | The first time a defragmenting program is run may require
| + | The first time a defragmenting program is run may require |
− | several hours if a hard drive is large and badly fractured with
| + | several hours if a hard drive is large and badly fractured with |
− | scattered files and clusters. It is a good idea to backup all
| + | scattered files and clusters. It is a good idea to backup all |
− | essential files prior to "defragging" just in case there is a
| + | essential files prior to "defragging" just in case there is a |
− | power failure during a long "defrag". Subsequent runs of the
| + | power failure during a long "defrag". Subsequent runs of the |
− | "defragger" produce runs of only a few minutes or so since the
| + | "defragger" produce runs of only a few minutes or so since the |
− | heavy work was done earlier. Essentially, "defragging" the hard
| + | heavy work was done earlier. Essentially, "defragging" the hard |
− | drive should be done regularaly, perhaps weekly. Defragging is
| + | drive should be done regularaly, perhaps weekly. Defragging is |
− | not a substitute for caching, ramdisks, or buffer - instead it
| + | not a substitute for caching, ramdisks, or buffer - instead it |
− | is a maintenance function which should be done regularly.
| + | is a maintenance function which should be done regularly. |
| | | |
− | Yet another possible avenue to improve disk performance is that
| + | Yet another possible avenue to improve disk performance is that |
− | of changing the disk interleave factor which we will discuss a
| + | of changing the disk interleave factor which we will discuss a |
− | bit later in this tutorial. By way of brief introduction: the
| + | bit later in this tutorial. By way of brief introduction: the |
− | disk interleave indicates how many revolutions of the magnetic
| + | disk interleave indicates how many revolutions of the magnetic |
− | platter are required to read all the sectors of data from the
| + | platter are required to read all the sectors of data from the |
− | spinning track. A ratio of 1:1 means all data can be read
| + | spinning track. A ratio of 1:1 means all data can be read |
− | sequentially. One sector of data after another.
| + | sequentially. One sector of data after another. |
| | | |
− | There is some overhead time required for the read/write head to
| + | There is some overhead time required for the read/write head to |
− | zip to the FAT area of the disk (if it is not in a cache or
| + | zip to the FAT area of the disk (if it is not in a cache or |
− | buffer) to determine location of the next sector along the disk
| + | buffer) to determine location of the next sector along the disk |
− | track.
| + | track. |
| | | |
− | For example, five clusters of data on a track might require four
| + | For example, five clusters of data on a track might require four |
− | trips back to the FAT track to find the cluster addresses even
| + | trips back to the FAT track to find the cluster addresses even |
− | on a completely defragmented disk. We will talk more about
| + | on a completely defragmented disk. We will talk more about |
− | cluster and defragmenting a bit later in this tutorial.
| + | cluster and defragmenting a bit later in this tutorial. |
| | | |
− | Nevertheless, depending on the speed of your central processor
| + | Nevertheless, depending on the speed of your central processor |
− | or CPU, using a program which tests and alters the interleave
| + | or CPU, using a program which tests and alters the interleave |
− | factor, IF THIS CAN BE DONE, may yield better performance. Most
| + | factor, IF THIS CAN BE DONE, may yield better performance. Most |
− | interleave adjustment software first performs a test to
| + | interleave adjustment software first performs a test to |
− | determine the current interleave, the possible changes and of
| + | determine the current interleave, the possible changes and of |
− | course how much performance time might be gained. A few of these
| + | course how much performance time might be gained. A few of these |
− | packages can alter the interleave with the files in place but
| + | packages can alter the interleave with the files in place but |
− | you should backup truly essential files before starting the
| + | you should backup truly essential files before starting the |
− | process. Interleave factor adjustment are mainly derived from
| + | process. Interleave factor adjustment are mainly derived from |
− | the CPU speed NOT the disk speed. Thus a fast AT or 80386
| + | the CPU speed NOT the disk speed. Thus a fast AT or 80386 |
− | equipped machine will more likely be able to take advantage of
| + | equipped machine will more likely be able to take advantage of |
− | an interleave adjustment.
| + | an interleave adjustment. |
| | | |
− | Tinkering with a hard drive for optimum results might best be
| + | Tinkering with a hard drive for optimum results might best be |
− | divided into two categories: DISK SUBSTITUTION and DISK
| + | divided into two categories: DISK SUBSTITUTION and DISK |
− | ALTERATION. DOS allows two clever ways substituting RAM memory
| + | ALTERATION. DOS allows two clever ways substituting RAM memory |
− | for disk memory.
| + | for disk memory. |
| | | |
− | In the first, using BUFFERS, the small CONFIG.SYS file on your
| + | In the first, using BUFFERS, the small CONFIG.SYS file on your |
− | hard drive is modified to contain a buffers statement. A sample
| + | hard drive is modified to contain a buffers statement. A sample |
− | might be: BUFFERS=20. A DOS buffer is an area of RAM memory
| + | might be: BUFFERS=20. A DOS buffer is an area of RAM memory |
− | capable of holding a 512 byte mirror image of a disk sector.
| + | capable of holding a 512 byte mirror image of a disk sector. |
− | This allows DOS to quickly search the buffer area for frequently
| + | This allows DOS to quickly search the buffer area for frequently |
− | used data instead of the slower disk. In the older XT class
| + | used data instead of the slower disk. In the older XT class |
− | machine, if you did not specify a buffer size, DOS defaulted to
| + | machine, if you did not specify a buffer size, DOS defaulted to |
− | 2 buffers while later versions of DOS default to about 10
| + | 2 buffers while later versions of DOS default to about 10 |
− | buffers. Most users settle on about 20 buffers but you can
| + | buffers. Most users settle on about 20 buffers but you can |
− | specify up to 99 with current releases of DOS. But you don't get
| + | specify up to 99 with current releases of DOS. But you don't get |
− | something for nothing. If you used the full 99 buffers
| + | something for nothing. If you used the full 99 buffers |
− | available, you would soak up 45K of your main RAM memory! The
| + | available, you would soak up 45K of your main RAM memory! The |
− | downside of using buffers is that more is not necessarily
| + | downside of using buffers is that more is not necessarily |
− | better.
| + | better. |
| | | |
− | Unfortunately, DOS searches the buffer area of RAM sequentially
| + | Unfortunately, DOS searches the buffer area of RAM sequentially |
− | rather than logically so if DOS requires data which is in the
| + | rather than logically so if DOS requires data which is in the |
− | buffer area, it will search each 512 byte area in sequence from
| + | buffer area, it will search each 512 byte area in sequence from |
− | top to bottom even though the data it needs may be at the end of
| + | top to bottom even though the data it needs may be at the end of |
− | the buffer. Logically, then, there is an optimum number of
| + | the buffer. Logically, then, there is an optimum number of |
− | buffers - too many used with a small program and you can slow
| + | buffers - too many used with a small program and you can slow |
− | things down, not enough and DOS will be forced to go out to the
| + | things down, not enough and DOS will be forced to go out to the |
− | disk to retrieve what it needs. If you rarely use the same data
| + | disk to retrieve what it needs. If you rarely use the same data |
− | within a program twice but load lots of different programs and
| + | within a program twice but load lots of different programs and |
− | data, a large number of buffers won't help. However if you need
| + | data, a large number of buffers won't help. However if you need |
− | frequent access to a certain data file or portion of that file,
| + | frequent access to a certain data file or portion of that file, |
− | buffers will help. Portions of the FAT are kept within the
| + | buffers will help. Portions of the FAT are kept within the |
− | buffers area, so dropping your buffers to zero has the damaging
| + | buffers area, so dropping your buffers to zero has the damaging |
− | effect that DOS must always go to the disk to read the FAT which
| + | effect that DOS must always go to the disk to read the FAT which |
− | isn't helpful either.
| + | isn't helpful either. |
| | | |
− | Another way of substituting RAM memory for disk memory involves
| + | Another way of substituting RAM memory for disk memory involves |
− | using a RAMDISK. The idea is to create in RAM memory an entire
| + | using a RAMDISK. The idea is to create in RAM memory an entire |
− | disk or a small portion of a disk. This works like magic on many
| + | disk or a small portion of a disk. This works like magic on many |
− | machines since the reading of tracks and sectors takes place at
| + | machines since the reading of tracks and sectors takes place at |
− | the high speed of RAM memory rather than the mechanically
| + | the high speed of RAM memory rather than the mechanically |
− | limited speed of the read/write heads on a floppy or hard drive.
| + | limited speed of the read/write heads on a floppy or hard drive. |
| | | |
− | But be careful. Three areas of difficulty can arise. First you
| + | But be careful. Three areas of difficulty can arise. First you |
− | must remember to take the data from a floppy or hard drive and
| + | must remember to take the data from a floppy or hard drive and |
− | move it into the RAMDISK. Many people do this automatically from
| + | move it into the RAMDISK. Many people do this automatically from |
− | within an AUTOEXEC.BAT file or may have several floppies, each
| + | within an AUTOEXEC.BAT file or may have several floppies, each |
− | with a different RAMDISK configuration depending on the task at
| + | with a different RAMDISK configuration depending on the task at |
− | hand. Copying data to the RAMDISK usually moves along briskly.
| + | hand. Copying data to the RAMDISK usually moves along briskly. |
− | Secondly you must sacrifice a large area of memory for the
| + | Secondly you must sacrifice a large area of memory for the |
− | RAMDISK which can no longer be used by your main program. Users
| + | RAMDISK which can no longer be used by your main program. Users |
− | of computers with extended or expanded memory usually choose to
| + | of computers with extended or expanded memory usually choose to |
− | put their RAMDISK in the extended or expanded memory area of RAM
| + | put their RAMDISK in the extended or expanded memory area of RAM |
− | so that precious main memory is not lost. Still, a small RAMDISK
| + | so that precious main memory is not lost. Still, a small RAMDISK |
− | can soak up 64K of RAM memory and one or two MEG RAMDISKS area
| + | can soak up 64K of RAM memory and one or two MEG RAMDISKS area |
− | common for many users. The third and most serious problem when
| + | common for many users. The third and most serious problem when |
− | using RAMDISKS is that they are volatile - switch off the
| + | using RAMDISKS is that they are volatile - switch off the |
− | machine or experience a power failure, and your data is lost
| + | machine or experience a power failure, and your data is lost |
− | forever! Rather than residing safely on a magnetic disk, the
| + | forever! Rather than residing safely on a magnetic disk, the |
− | data is "floating" in RAM memory and should be - MUST BE! -
| + | data is "floating" in RAM memory and should be - MUST BE! - |
− | written to a disk before the machine is powered down.
| + | written to a disk before the machine is powered down. |
| | | |
− | Many applications fly with a RAMDISK. Users of word processors
| + | Many applications fly with a RAMDISK. Users of word processors |
− | find that moving the spelling checker and thesaurus to the
| + | find that moving the spelling checker and thesaurus to the |
− | RAMDISK speeds up things considerably since these are used
| + | RAMDISK speeds up things considerably since these are used |
− | heavily in a random manner. Spreadsheet users find that reading
| + | heavily in a random manner. Spreadsheet users find that reading |
− | and writing short data files to RAMDISKS is a boon. Programs
| + | and writing short data files to RAMDISKS is a boon. Programs |
− | which use overlay files or temporary files as well as
| + | which use overlay files or temporary files as well as |
− | programming compilers benefit from RAMDISK use. Batch files
| + | programming compilers benefit from RAMDISK use. Batch files |
− | which are disk intensive as well as small utilities really
| + | which are disk intensive as well as small utilities really |
− | sprint when placed on a RAMDISK. Basically, any program file
| + | sprint when placed on a RAMDISK. Basically, any program file |
− | which is frequently used and loaded/unloaded repeatedly to a
| + | which is frequently used and loaded/unloaded repeatedly to a |
− | disk during normal computer operation is an excellent candidate
| + | disk during normal computer operation is an excellent candidate |
− | for RAMDISK placement. DOS contains a RAMDISK which is called by
| + | for RAMDISK placement. DOS contains a RAMDISK which is called by |
− | using the statement DEVICE=VDISK.SYS or DEVICE=RAMDRIVE.SYS (if
| + | using the statement DEVICE=VDISK.SYS or DEVICE=RAMDRIVE.SYS (if |
− | you are using MSDOS) which is placed in your CONFIG.SYS file.
| + | you are using MSDOS) which is placed in your CONFIG.SYS file. |
− | Your DOS manual details the specifics such as stating the size
| + | Your DOS manual details the specifics such as stating the size |
− | of RAMDISK and giving it a drive letter. You must still copy
| + | of RAMDISK and giving it a drive letter. You must still copy |
− | your target files into the RAMDISK and place it in the search
| + | your target files into the RAMDISK and place it in the search |
− | path (with the PATH= command) as we mentioned in a previous
| + | path (with the PATH= command) as we mentioned in a previous |
− | tutorial. And the RAMDISK should always be the first drive
| + | tutorial. And the RAMDISK should always be the first drive |
− | letter mentioned in the path command so that DOS searches it
| + | letter mentioned in the path command so that DOS searches it |
− | first for optimum results.
| + | first for optimum results. |
| | | |
− | Yet another area of investigation is that of CACHE software.
| + | Yet another area of investigation is that of CACHE software. |
− | Essentially a CACHE is an extension of the buffers idea we
| + | Essentially a CACHE is an extension of the buffers idea we |
− | discussed earlier. But the twist is that the CACHE is searched
| + | discussed earlier. But the twist is that the CACHE is searched |
− | intelligently by a searching algorithm within the CACHE software
| + | intelligently by a searching algorithm within the CACHE software |
− | rather than from top to bottom as with the more typical DOS
| + | rather than from top to bottom as with the more typical DOS |
− | buffer search system. Disk CACHE software can be obtained as
| + | buffer search system. Disk CACHE software can be obtained as |
− | either commercial software or shareware. As with a RAMDISK, the
| + | either commercial software or shareware. As with a RAMDISK, the |
− | CACHE requires a chunk of RAM memory to operate. This can be
| + | CACHE requires a chunk of RAM memory to operate. This can be |
− | extended memory, expanded memory or main RAM memory. Some
| + | extended memory, expanded memory or main RAM memory. Some |
− | manufacturers include a CACHE program with the software package
| + | manufacturers include a CACHE program with the software package |
− | or DOS disk. A CACHE is a sophisticated type of RAMDISK, in a
| + | or DOS disk. A CACHE is a sophisticated type of RAMDISK, in a |
− | rough sense.
| + | rough sense. |
| | | |
− | CACHE software allocates a large area of memory for storage of
| + | CACHE software allocates a large area of memory for storage of |
− | frequently used disk data. This data is updated by an
| + | frequently used disk data. This data is updated by an |
− | intelligent CACHE search algorithm in an attempt to "guess"
| + | intelligent CACHE search algorithm in an attempt to "guess" |
− | which tracks of a disk you might read or need next. The CACHE
| + | which tracks of a disk you might read or need next. The CACHE |
− | also stores the most frequently used disk data and attempts to
| + | also stores the most frequently used disk data and attempts to |
− | remove less frequently used data. Whenever DOS requests disk
| + | remove less frequently used data. Whenever DOS requests disk |
− | data, the CACHE software first tries to fill the order from data
| + | data, the CACHE software first tries to fill the order from data |
− | currently stashed in the CACHE which prevents a slower disk
| + | currently stashed in the CACHE which prevents a slower disk |
− | search.
| + | search. |
| | | |
− | When data is written from the program to the CACHE, first a disk
| + | When data is written from the program to the CACHE, first a disk |
− | write is done to prevent data loss in case of power failure and
| + | write is done to prevent data loss in case of power failure and |
− | then the data is stashed in the CACHE in case it is needed
| + | then the data is stashed in the CACHE in case it is needed |
− | again. Usually the hard drive data is the target of the CACHE
| + | again. Usually the hard drive data is the target of the CACHE |
− | activity, but a floppy disk could also be cached. All CACHE
| + | activity, but a floppy disk could also be cached. All CACHE |
− | software allows you to allocate the size of the CACHE as well as
| + | software allows you to allocate the size of the CACHE as well as |
− | the drive or drives to be cached. And some even allow you to
| + | the drive or drives to be cached. And some even allow you to |
− | specify exact files or data to be cached. The key is that high
| + | specify exact files or data to be cached. The key is that high |
− | use data lives in RAM memory which keeps tedious disk access
| + | use data lives in RAM memory which keeps tedious disk access |
− | times low. In general, if your computer has a megabyte or more
| + | times low. In general, if your computer has a megabyte or more |
− | of memory and a speedy processor such as an 80286 or 80386
| + | of memory and a speedy processor such as an 80286 or 80386 |
− | either or both a CACHE or RAMDISK option does improve
| + | either or both a CACHE or RAMDISK option does improve |
− | performance.
| + | performance. |
| + | |
| + | As we leave hard disk boot camp, let's finally look at hard |
| + | drive formatting processes. Two basic formatting operations are |
| + | of concern: physical formatting or low level formatting and |
| + | logical or high level formatting. When you use the format |
| + | program on a floppy disk both low level and high level |
| + | formatting is accomplished. On a hard disk, formatting performs |
| + | only logical or high level formatting. On a hard disk, low level |
| + | formatting is usually done to a disk before shipment. As an |
| + | aside, the FDISK command of DOS has little to do with either |
| + | type of formatting, but is a method of partitioning or arranging |
| + | the data onto the hard drive tracks. Each disk platter is |
| + | separated into circular concentric tracks where data is stored |
| + | as we saw earlier. During physical formatting the tracks are |
| + | divided into further subdivisions called clusters and further |
| + | yet into sectors. High level formatting involves the specific |
| + | ordering of the space for the exclusive use of DOS and is a bit |
| + | more analogous to the formatting of a floppy disk. |
| | | |
− | As we leave hard disk boot camp, let's finally look at hard
| + | Some software programs of use by hard drive owners: |
− | drive formatting processes. Two basic formatting operations are
| |
− | of concern: physical formatting or low level formatting and
| |
− | logical or high level formatting. When you use the format
| |
− | program on a floppy disk both low level and high level
| |
− | formatting is accomplished. On a hard disk, formatting performs
| |
− | only logical or high level formatting. On a hard disk, low level
| |
− | formatting is usually done to a disk before shipment. As an
| |
− | aside, the FDISK command of DOS has little to do with either
| |
− | type of formatting, but is a method of partitioning or arranging
| |
− | the data onto the hard drive tracks. Each disk platter is
| |
− | separated into circular concentric tracks where data is stored
| |
− | as we saw earlier. During physical formatting the tracks are
| |
− | divided into further subdivisions called clusters and further
| |
− | yet into sectors. High level formatting involves the specific
| |
− | ordering of the space for the exclusive use of DOS and is a bit
| |
− | more analogous to the formatting of a floppy disk.
| |
| | | |
− | Some software programs of use by hard drive owners:
| + | The following two programs perform low level formatting and |
| + | simple diagnostic routines on a hard drive: |
| | | |
− | The following two programs perform low level formatting and
| + | Disk Manager and CheckIt |
− | simple diagnostic routines on a hard drive:
| |
| | | |
− | Disk Manager and CheckIt
| + | Data recovery and "unerasing" programs also containing |
| + | diagnostic routines are: |
| | | |
− | Data recovery and "unerasing" programs also containing
| + | PC Tools Deluxe, Norton Utilities, Mace Utilities |
− | diagnostic routines are:
| |
| | | |
− | PC Tools Deluxe, Norton Utilities, Mace Utilities
| + | Extensive diagnostic and maintenance/data repair functions as |
| + | well as interleave alteration and head parking are offered by: |
| | | |
− | Extensive diagnostic and maintenance/data repair functions as
| + | SpinRite II, Optune, Disk Technician |
− | well as interleave alteration and head parking are offered by:
| |
| | | |
− | SpinRite II, Optune, Disk Technician
| + | Shareware programs with unerase functions include: |
| | | |
− | Shareware programs with unerase functions include:
| + | Bakers Dozen |
| | | |
− | Bakers Dozen
| + | Shareware programs with defragmentation capabilities include: |
| | | |
− | Shareware programs with defragmentation capabilities include:
| + | SST and PACKDISK. |
| | | |
− | SST and PACKDISK.
| + | Tutorial finished. Be sure to order your FOUR BONUS DISKS which |
| + | expand this software package with vital tools, updates and |
| + | additional tutorial material for laptop users! |
| | | |
− | Tutorial finished. Be sure to order your FOUR BONUS DISKS which
| |
− | expand this software package with vital tools, updates and
| |
− | additional tutorial material for laptop users! Send $20.00 to
| |
− | Seattle Scientific Photography, Department LAP, PO Box 1506,
| |
− | Mercer Island, WA 98040. Bonus disks shipped promptly! Some
| |
− | portions of this software package use sections from the larger
| |
− | PC-Learn tutorial system which you will also receive with your
| |
− | order. Modifications, custom program versions, site and LAN
| |
− | licenses of this package for business or corporate use are
| |
− | possible, contact the author. This software is shareware - an
| |
− | honor system which means TRY BEFORE YOU BUY. Press escape key to
| |
− | return to menu.
| |
− | </pre>
| |
| | | |
| | | |
| [[Category:Computing]] | | [[Category:Computing]] |
| + | [[Category:Essays]] |