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             Disk Manager 5.10 and Windows - (Technical Version)
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NOTE: This level of information is not required by most users, therefore,
Ontrack Technical Support will not provide detailed support regarding its
contents.

Ontrack has incorporated enhancements to version 5.10 of our Disk Manager
hard disk installation software, or more specifically our device driver
DMDRVR.BIN, to improve compatibility with Microsoft Windows 3.1 permanent
swapfiles.  In most cases you will now be able to use a permanent swapfile
with Windows 386 enhanced mode.  The information provided in this document
is only relevant to users of 386 and 486 class computers, as it relates to
Windows 386 enhanced mode exclusively.  Although not effected by changes to
DMDRVR.BIN, information on compatibility with Windows 3.1 FastDisk support
is also provided.

NOTE: The information that follows considers only Windows 3.1 and Disk
Manager software 5.10.  Permanent swapfiles can not be used if previous
versions of either software is used.  Also, other elements, such as disk
compression software, may also inhibit permanent swapfile creation or
FastDisk support.

PERMANENT SWAPFILE COMPATIBILITY

Historically permanent swapfiles have not been available on systems using
DMDRVR.BIN.  This is because DMDRVR.BIN allows conditions to exist in your
system which Windows does not adjust for when accessing a permanent
swapfile.  There are three conditions involving DMDRVR.BIN, and the
XBIOS.OVL INT13 overlay allow, that can cause incompatibly with permanent
swapfiles.  These are the same conditions that allow Ontrack partitions to
transcend the limitations of DOS partitions.  The three conditions are
explained in detail below.  A system must be configured within Windows
limitations for all three of these conditions to be permanent swapfile
compatible.

NON-HOMOGENEOUS DRIVES

     A drive is said to be non-homogeneous when the number of heads and
     sectors-per-track (SPT) are not the same in all partitions.

     DOS can only access your hard drive using the parameters specified the
     ROM BIOS drive table entry, referenced by your CMOS drive type.  As a
     result, the number of heads and SPT used in any DOS partitions,
     including DOS partitions created by Disk Manager software, will match
     the parameters of the drive type set in CMOS.  If there is not an
     accurate drive table entry available for the drive, there will be a
     loss of hard drive capacity.  For example, if you have a drive that is
     1024x12x17 (102MB) but the closest entry in your drive table is
     1024x9x17 (76.5MB) you would loose 25.5MB of capacity if only DOS
     partitions are used.

     Ontrack WRITE-READ and READ-ONLY partitions are not subject to drive
     table limitations.  The Disk Manager program (DM.EXE) uses the drives
     actual parameters when creating WRITE-READ and READ-ONLY partitions and
     writes these parameters to the drive.  When DMDRVR.BIN is loaded at
     boot time, it reads the parameters from the drive and resets the disk
     subsystem so it can access the entire drive.  Taking the scenario
     above, but allocating only 40 cylinders (3MB) of the drive for a DOS
     bootable partition (you can not boot from an Ontrack partition) and
     allocating the remainder of the drive in WRITE-READ partitions, you
     would loose only 1MB of capacity.
     While DMDRVR.BIN can transcend the limitations of your computers ROM
     BIOS and make additional space available, the combination of DOS and
     WRITE-READ partitions above results in a non-homogeneous drive.  This
     will not normally present any problems for either DOS or Windows. 
     DMDRVR.BIN is attached to DOS as a block device driver.  When the drive
     is accessed from a DOS level, either INT21 or INT25/26, calls are made
     through DMDRVR.BIN, which adjusts for the non-homogeneous condition. 
     Windows will normally access the drive through DOS and through
     DMDRVR.BIN, which again can adjust for the for the non-homogeneous
     condition.

     For Windows to use a permanent swapfile it must be able to access the
     disk at the INT13 level, below DOS and DMDRVR.BIN.  While this low
     level access is certainly justifiable, Windows does not gain
     DMDRVR.BIN's support for non-homogeneous drives when accessing
     permanent swapfiles.  Windows itself does not adjust for this condition
     so it will not be able to successfully access a permanent swapfile on a
     non-homogeneous drive.  Windows could, however, successfully access a
     permanent swapfile on a WRITE-READ partition on a homogeneous drive. 

     To prevent problems, when you attempt to create a permanent swapfile
     Windows or Setup will check the drives in the system to see if there
     are any partitions type present that could allow the drive to be
     non-homogeneous.  Since WRITE-READ and READ-ONLY partitions allow this
     condition, a message dialogue is presented indicating that a
     partitioning scheme on your hard drive does not permit the creation of
     a permanent swapfile, suggesting that you create a temporary swapfile
     (which by the way works fine).  No attempt is made to determine if the
     drive is actually non-homogeneous, so permanent swapfiles are
     unnecessarily prohibited on homogeneous drives.

     In the interest of allowing permanent swapfiles, enhancements have been
     made to DMDRVR.BIN to overcome this unnecessary restriction for
     homogenous drives.  Two new Ontrack partition types,
     WRITE-READ-HOMOGENEOUS and READ-ONLY-HOMOGENEOUS, are now supported. 
     These new partition types are used exclusively on homogenous drives,
     hence Windows and Setup will allow swapfile creation on
     WRITE-READ-HOMOGENEOUS partitions.  The new DMDRVR.BIN will
     automatically determine if your drive is homogenous or non-homogeneous. 
     If your drive is homogenous all WRITE-READ and READ-ONLY partitions
     will be converted to WRITE-READ-HOMOGENEOUS and READ-ONLY-HOMOGENEOUS
     partitions.  If your drive is non-homogeneous Ontrack partitions will
     remain WRITE-READ and READ-ONLY.  If your drive does not have more that
     1024 cylinders, DMDRVR.BIN will perform this conversion automatically
     the first time your system is booted with the new DMDRVR.BIN installed. 
     If your drive is over 1024 cylinders, you will have to manually enable
     this support (see below). 

     If your drive is non-homogeneous you must eliminate that condition
     before you will be able to use Windows permanent swapfiles.  Depending
     on your system configuration you may need to perform one of the
     following.

     1)   Reconfigure a dual drive System.

          If you have two different hard drives on an AT compatible
          controller card, it is possible that one of your drives has a
          matching head and SPT entry in CMOS, while the other may not.  If
          your second drive can have its head and SPT values represented by
          a CMOS entry (cylinders are unimportant so long as the actual
          cylinder count of the drive is not exceeded) you could make your
          system permanent swapfile compatible by backing up files on both
          drives and reinstalling your system.  Reinstall your hardware
          making the drive having a homogeneous drive table entry the
          primary drive (80h) and use only WRITE-READ and READ-ONLY
          partitions on the secondary drive (81h).  After reinstalling, the
          new DMDRVR.BIN will automatically make your system permanent
          swapfile compatible, unless you have a drive over 1024 cylinders
          (see below).

     2)   Explore BIOS level support options.

          Check your drive type table for an entry that has the same heads
          and SPT as your drive.  You can view your entire drive table using
          DM.EXE in manual mode.  It is possible that the drive was
          installed using a less than optimal drive type, reinstalling with
          an appropriate drive type will allow your system to be made
          permanent swapfile compatible by the new DMDRVR.BIN.  You could
          also set up a user defined drive type if available.

          If you have an older AT, with spare ROM sockets, Ontrack has an
          option ROM (SuperProms) that will provide you with additional
          drive types to choose from.  Reinstalling using a SuperProms drive
          type with the same heads and SPT as your drive will allow your
          system to be permanent swapfile compatible by the new DMDRVR.BIN.

          If you have a controller card with BIOS capable of presenting your
          drives parameters (most ESDI and RLL controller will do this) use
          its BIOS routine, accessed through DEBUG to reinstall initialize
          your drive.  If the controller is allowed to initialize the drive
          it will load the appropriate parameters when your system is
          booted, this will eliminate the non-homogeneous condition.  If you
          initialize with BIOS, you can still use DM.EXE to partition and
          prepare the drive, however, you must install the drive with
          standard parameters and not allow DM.EXE to initialize the drive.

     3)   Sacrifice space for permanent swapfile compatibility.

          If you must have a permanent swapfile and can not make your drive
          homogeneous following the previous suggestions, you can reinstall
          your drive using only the head and SPT values specified in CMOS. 
          You can use DM.EXE in manual mode to do this, when you select your
          drive from the drive list choose to edit the parameters and change
          the heads and or SPT values to match the CMOS parameters. 
          Reinstalling in this fashion will make your system permanent
          swapfile compatible but will also cause a loss of usable drive
          capacity.

LOGICAL SECTOR SIZES GREATER THAN 512 BYTES

     NOTE: DOS 4.0, 4.01 and 5.0 (and Compaq 3.31) require that all logical
     sectors be 512 bytes.  If you are using one of these DOS versions, the
     information provided in this section is not applicable to your
     configuration.

     Under DOS 3.30 and previous versions, the number of logical sectors
     that can exist in one partition is limited, but the logical sector size
     is not.  Since DOS itself will use only 512 byte sectors, the largest a
     DOS partition can be under these versions is 32MB.  In order to support
     partitions larger than 32MB under these DOS versions, Disk Manager
     software increases size of the logical sector.  The logical sector size
     used is dependent on partition size.  On partitions of up to 32MB all
     logical sectors will be the default 512 bytes.  To exceed 32MB the
     sector size is increased to 1024 bytes, to exceed 64MB the sector size
     is increased to 2048 bytes.  This progression continues with the
     largest possible partition of 512MB using an 8192 byte sector.  The
     cluster size in any partition over 16MB will be four times the logical
     sector size, under 16MB it is 4096 bytes.

     Since Disk Manger's support for large partitions operates completely
     with in the rules for DOS 3.30 and previous versions, it does not
     normally present a problem.  All accesses to the drive made through DOS
     INT21 and INT25/26 are handled correctly by DOS and DMDRVR.BIN and
     sector size need not be considered.  When Windows accesses the drive
     through DOS, as it generally does, it is not affected by logical sector
     size. 

     When Windows accesses a permanent swapfile it does so at the INT13
     level, below DOS and DMDRVR.BIN.  While this low level access is
     certainly justifiable, Windows does not take into account the
     possibility that the logical sector size could be larger than 512
     bytes.  As a result Windows will not be able to successfully access a
     permanent swapfile on drive with partitions created with greater than
     512 byte sectors.  Windows could, however, successfully access a
     permanent swapfile on a WRITE-READ if the sector size in all partition
     was 512 bytes.

     To prevent problems, Windows and Setup will check the drives in your
     system to determine if there are any partitions present that allow
     larger than 512 byte sectors.  Since WRITE-READ and READ-ONLY
     partitions allow sector sizes larger than 512 bytes, Windows and Setup
     will not allow a permanent swapfile to be created.

     The enhancements made to DMDRVR.BIN allow it to make your partitions
     compatible with Windows permanent swapfiles only if all logical sector
     sizes on all partitions are 512 bytes.  In order to take advantage of
     the new features described above, you will need to reconfigure your
     system to make all logical sector sizes 512 bytes.  There are two ways
     that you can accomplish this.

     1)   Reinstall your system with all partitions 32MB or less.

          You can continue to use DOS 3.30 or previous version if you backup
          your files and reinstall your system, with DM.EXE, creating only
          partitions of 32MB or less.  After the system is reinstalled with
          all 512 byte logical sectors, it will automatically be made
          permanent swapfile compatible by the new DMDRVR.BIN, unless you
          have a drive with more than 1024 cylinders (see below).  This will
          be quite a bit of work and drastically limits flexibility when
          configuring your system.  Option number 2 provides for a better
          solution.

     2)   Reinstall your system with a newer version of DOS.

          By far the best way to do this is to backup your files and
          reinstall your system, using DM.EXE, under DOS 5.0.  Any version
          of DOS later than 4.0 (and Compaq 3.31) will use only 512 byte
          sectors regardless of partition size, however, the Windows 3.1 is
          optimized for DOS 5.0 making it the version of choice.  After the
          system is reinstalled with DOS 4.0 or later, it will automatically
          be made permanent swapfile compatible, unless you have a drive
          over 1024 cylinders (see below). 

DRIVES WITH MORE THAN 1024 CYLINDERS

     Many drives may be homogeneous and use 512 byte sectors, but have more
     than 1024 cylinders.  Although permanent swapfiles can be used on
     homogeneous drives with over 1024 cylinders, the new DMDRVR.BIN will
     not automatically convert partitions on these drives.  This is because
     Windows accesses a permanent swapfile at a level below both DOS and
     DMDRVR.BIN, and can not access more than 1024 cylinders.  As a result
     the permanent swapfile will not be usable unless it resides entirely
     within the first 1024 cylinders of the drive.  You must keep this
     limitation in mind when creating your permanent swapfile.

     To enable DMDRVR.BIN to convert partitions on drives with more than
     1024 cylinders, you need to add a /P (enable Partition conversion)
     switch to the DMDRVR device statement.  If the drive is homogeneous,
     any WRITE-READ and READ-ONLY partitions will be changed to
     WRITE-READ-HOMOGENEOUS and READ-ONLY-HOMOGENEOUS partitions for
     permanent swapfile compatibility.  If the drive is non-homogeneous
     Ontrack partitions will remain WRITE-READ and READ-ONLY.  The modified
     device statement should appear as below.

     DEVICE=C:\DMDRVR.BIN /P

     During permanent swapfile creation Windows and Setup access the drive
     through DOS.  As a result, it is possible to create a permanent
     swapfile that is not within the first 1024 cylinders of the drive. 
     When Windows is restarted, after the such a swapfile is created, it
     will present an error message indicating that the swapfile is corrupt. 
     This results from Windows inability to access it correctly beyond 1024
     cylinders.  Windows will continue to load using a temporary swapfile,
     no data corruption will result. 

     If you receive a corrupt swapfile message when starting Windows, after
     creating a swapfile on a drive with more than 1024 cylinders, don't
     panic and call Microsoft.  The problem is most likely that all or part
     of the swapfile is located above 1024 cylinders.  You should try the
     following steps to eliminate this condition.

     1)   Create the permanent swapfile on a DOS partition.

          Since the DOS partition itself must reside entirely within the
          first 1024 cylinders, the swapfile will too.  This is the surest
          way to eliminate a corrupt swapfile error.  You may need to
          optimize a partition to get enough contiguous free space to create
          a permanent swapfile of the size you desire.

     2)   Create the permanent swapfile on a WRITE-READ-HOMOGENEOUS
          partition below 1024 cylinders.

          If your DOS partition(s) are too small, or are filled with files,
          and you have a WRITE-READ-HOMOGENEOUS partition that resides
          within the first 1024 cylinders will also make an excellent host
          for a permanent swapfile.  Since the partition resides below 1024
          cylinders, the swapfile will too.  You can get the ending
          cylinders for your partitions by running DM.EXE in manual mode and
          displaying the partition table.  You may need to optimize a
          partition to get enough contiguous free space to create a
          permanent swapfile of the size you desire.

     3)   Create the permanent swapfile on a WRITE-READ-HOMOGENEOUS
          partition that crosses the 1024th cylinder.

          This should only be considered if you do not have a partition
          within the first 1024 cylinders that is large enough to host the
          permanent swapfile.  If you have a partition large enough with the
          first 1024 cylinders, copy files out of it and into one that
          crosses or exceeds 1024th cylinder and create the swapfile there.
          Creating a permanent swapfile on a partition that crosses the
          1024th cylinder is very likely to cause a corrupt swapfile error.
          If you don't have a partition within the first 1024 cylinders, you
          may find it much less frustrating to backup the drive and
          repartition it, allocating sufficient space in a DOS partition (or
          WRITE-READ-HOMOGENEOUS under 1024) to host the permanent swapfile. 
          This is a lot of work, but worth the effort, particularly if you
          decide to change the size of your swapfile.

          If you are intent on creating a permanent swapfile on a
          WRITE-READ-HOMOGENEOUS partition that crosses the 1024 cylinder
          boundary, you will need to free sufficient contiguous space within
          the first 1024 cylinders.  If your drive is relatively empty it
          may not be hard to allocate a permanent swapfile.  Remember that
          the swapfile must be contiguous, you will want to allow plenty of
          padding to your swapfile size as you may not be able to enlarge it
          later.  If your drive is full you may need to back off and delete
          a good deal of files, then optimize the drive to get enough
          contiguous space within the first 1024 cylinders.

COMPATIBILITY WITH WINDOWS 3.1 FASTDISK

     FastDisk refers to a set of device drivers that are an internal part of
     Windows 3.1.  It allows Windows to communicate directly with AT
     register set compatible, also called WD1003 compatible, disk drive
     controllers.  Most MFM, RLL, IDE and many ESDI controllers fall into
     this category.  SCSI host adapters and ESDI adapters with translations
     schemes that exceed 16 heads are not supported by FastDisk at this
     time.  FastDisk support is not required to run Windows 3.1, in fact it
     is not even enabled by default.  Refer to your Windows documentation
     for more information on what FastDisk is and how to it can be enabled
     if your hardware supports it.

     Since FastDisk communicates directly with the registers on the
     controller, it bypasses DMDRVR.BIN and XBIOS.OVL completely.  Also
     since FastDisk uses the same command structures as BIOS INT13 to access
     a drive, it can not access above 1024 cylinders.  If Windows detects
     that XBIOS is loaded to provide over 1024 cylinder support, it will
     disable FastDisk.  Windows will allow FastDisk to be used with
     DMDRVR.BIN on drives not over 1024 cylinders, provided the controller
     itself is FastDisk compatible.
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