Network Support Library/RoseWare - Network Support Library.iso/nwlite/faxdoc.exe/2851.TXT

Text File | 1993-05-14 | 29KB | 640 lines

                                     FYI

(Note:  The origin of this information may be internal or external to Novell.
Novell makes every effort within its means to verify this information.
However, the information provided in this document is FOR YOUR INFORMATION
ONLY.  Novell makes no explicit or implied claims to the validity of this
information.)

          TITLE:    NLCache
   DOCUMENT ID#:    FYI.P.6121
           DATE:    28JAN93
        PRODUCT:    NetWare Lite
PRODUCT VERSION:    All versions
     SUPERSEDES:    FYI.P.6075
 LITE FAX DOC #:    2851

SYMPTOM

     NA

ISSUE/PROBLEM

                                   NLCache

     NETWARE LITE CACHING BENEFITS

     NetWare Lite Cache makes your computer run three to six times faster by
     reducing the time your computer spends waiting for the hard disk.
     Caching makes your computer run faster and your hard drive last longer.

                              *****  WARNING  *****

     NetWare Lite Cache should not be used concurrently with another caching
     software.  If you choose to use a different cache program instead of
     NLCache, you must disable the cache's delayed writes in NLCINST under
     Deferred write delay.  Together they may cause problems.

     HOW NETWARE LITE CACHE WORKS

     NetWare Lite Cache keeps copies of data read from the disk in a memory
     area called a cache.  When a disk read is requested, NetWare Lite Cache
     checks to verify if the data is already in the cache.  If it is, NetWare
     Lite Cache delivers the data directly from the cache.  If it is not, the
     disk read is performed and a copy of the data is put in the cache.

     NetWare Lite Cache's LookAhead option adjusts the disk transfers to cache
     data, even before you need it, by reading entire blocks of sectors for
     future use.  LookAhead makes big improvements in disk throughput even
     with a small cache.  When disk writes are requested, NetWare Lite Cache
     determines if the data is in the cache and if it has changed.  If it has
     not changed, (determined by checksum) NetWare Lite Cache does not rewrite
     data to the disk.

     NetWare Lite Cache's optional delayed write feature speeds up disk
     operations even more by combining multiple disk writes into a single
     write.  Also, NetWare Lite Cache can turn off the delayed write feature
     (in NLCINST) and function as a write-through cache.

     If you have a power failure or reset the machine when using the delayed
     write feature, you may lose data because the data written to the cache in
     RAM is not written to the hard disk or floppy disk until the delayed

     write is complete.  When using delayed write, always exit programs
     correctly.

     The NetWare Lite NLCINST program helps you select the correct cache
     program for the type of memory your computer uses.

     ■    NLCACHEC is for computers with only conventional memory (memory up
          to 640 KB).

     ■    NLCACHEX is for computers with extended memory (memory above
          conventional, starting above 1024 KB).

     ■    NLCACHEM is for computers with expanded memory (special or paged
          memory that requires a device driver).

     You can use only one disk caching program at a time.  If your computer
     has both expanded memory and extended memory, use either NLCACHEX or
     NLCACHEM.

     INSTALLING NETWARE LITE CACHE

     The NetWare Lite Cache programs are copied to your hard drive when you
     initially install NetWare Lite.  If you specify that you want to use the
     NetWare Lite cache during installation, the proper command will be
     automatically added to the STARTNET.BAT file--the file which loads the
     network into memory.

     The INSTALL program recognizes the type of memory (conventional,
     expanded, extended) your computer has and how much memory is available.
     If your computer has 1 MB or more of free memory, the INSTALL program
     defaults the "Use NLCACHE and load it from STARTNET.BAT" option to YES.
     (This option is under STEP 2 "Preview changes to DOS startup files.")  If
     you want a cache, leave the option set to yes.  A NetWare Lite Startup
     command line, which includes the applicable NetWare Lite Cache program
     name (NLCACHEC, NLCACHEX, or NLCACHEM) and a number equal to half of the
     free memory (for the cache), will be included in STARTNET.BAT.  When
     STARTNET.BAT is run, the cache program loads using half of the free
     memory for the cache area.  If you do not want a cache, change the option
     to NO.

     To create or modify the cache startup command line from the DOS prompt,
     type NLCINST.  The current cache startup command line (if any) will be
     displayed.  Follow the instructions on the screen.  You can stop
     modifying or creating the cache startup command line at any time by
     pressing <Esc> repeatedly until the DOS prompt appears.  The new startup
     selections will take effect the next time you boot your computer.

     INSTALLING AS A TSR

     If you put the cache startup command in batch file such as AUTOEXEC.BAT
     or STARTNET.BAT or manually type it at the DOS prompt, the NetWare Lite
     Cache will be loaded as a TSR.  When the NetWare Lite Cache is loaded as
     a TSR, it can be unloaded by using the /Q option.  If you put the cache
     startup command in CONFIG.SYS, NetWare Lite Cache is loaded as a device
     driver and cannot be unloaded with the /Q option.

     INSTALLING AS A DEVICE DRIVER

     You must use DOS 3.0 or higher to load the cache as a device driver.
     NetWare Lite Cache requires slightly less memory when it is loaded as a
     device driver than when it is loaded as a TSR.  (DOS assigns TSRs a copy

     of the environment and a 128 byte control block.  Device drivers do not
     have a copy of the environment or the 128 byte control block).

     Start NetWare Lite Cache as a device driver by putting one of the
     following commands in your CONFIG.SYS file:

     KEY TERMS

     [path]

          Directory where the NetWare Lite Cache programs are located.

     [size]

          Amount of memory (specify kilobytes) you want to allocate to the
          cache.  If you do not specify a value, NetWare Lite Cache uses all
          free memory for the cache.

     [start]

          Starting address in extended memory for the cache.  Extended memory
          addresses begin above 1024 KB.  If you do not specify a starting
          address, NetWare Lite Cache uses the first available memory area.
          This is the best choice for most installations because it allows
          NetWare Lite Cache to put the control tables into extended memory.
          However, you may specify a specific address for NetWare Cache to
          use.

     [options]

          One or more startup command options.  See the "Cache Startup
          Commands" section of this document.  If you put the cache startup
          command in your CONFIG.SYS file, NetWare Lite Cache loads as a
          device driver each time you boot your computer. (Remember, as a
          device driver it cannot be unloaded with the /Q option.)  All other
          control options work as described in the "Netware Lite Cache
          Control" section of this document.  To Manually Create or Modify the
          Cache Startup Command as a TSR, start NetWare Lite Cache program by
          entering the cache startup command line at the DOS prompt or by
          including it in either AUTOEXEC.BAT or STARTNET.BAT.

       TYPE OF
     DEVICE DRIVER       CACHE STARTUP COMMAND MEMORY

     Conventional   Format:   DEVICE=[path] NLCACHEC.EXE [size] [options]

                    Example:  DEVICE=C:\NWLITE\NLCACHEC.EXE 128 /T=2
                              (The cache size would be 128 KB.  The maximum
                              write delay would be 2 seconds.)

     Extended       Format:   DEVICE=[path] NLCACHEX.EXE [size] [start]
                              [options]

                    Example:  DEVICE=C:\NWLITE\NLCACHEX.EXE 2048 D000 /T=5
                              (The cache size would be 2048 KB.  The starting
                              address would be D000.  The maximum write delay
                              would be 5 seconds.)

     Expanded       Format:   DEVICE=[path] NLCACHEM.EXE [size][options]


                    Example:  DEVICE=C:\NWLITE\NLCACHEM.EXE 512 /T=5/B=16
                              (The cache size would be 512 KB.  The maximum
                              write delay would be 5 seconds.  The LookAhead
                              buffer size would be 16KB.)

     TYPE OF MEMORY TSR CACHE STARTUP COMMAND LINE

     Conventional   Format:   NLCACHEC [size] [options]

                    Example:  NLCACHEC 128 /T=5
                              (The cache size would be 128 KB.  The maximum
                              write delay would be 5 seconds.)

     Extended       Format:   NLCACHEX [size] [start] [options]

                    Example:  NLCACHEX 1024 D000 /T=2
                              (The cache size would be 1024 KB.  The starting
                              address would be D000.  The maximum write delay
                              would be 2 seconds.)

     Expanded       Format:   NLCACHEM [size] [options]

                    Example:  NLCACHEM 512 /T=2
                              (The cache size would be 512 KB.  The maximum
                              write delay would be turned off so the cache
                              becomes a write-through cache.)

     CACHE STARTUP COMMANDS

     /A=  Sector Chain Limit

          ■    Use with NLCACHEC, NLCACHEX, and NLCACHEM.

          ■    It suppresses caching of read/write requests larger than the
               limit value.  The limit value range is from 1 to 128 sectors
               (128 sectors is the maximum number of sectors DOS allows).

          ■    Use it to tune the cache for unusual cases where programs are
               effectively flushing your cache by doing large reads.  If you
               select a sector limit value less than the maximum (128), large
               reads are not cached.

          ■    If this is not used, NetWare Lite Cache selects a best-fit
               limit value.  For cache sizes smaller than 256 KB, a /A= value
               larger than the best fit value is ignored.

     /B=  LookAhead Buffer Size

          ■    Use with NLCACHEC, NLCACHEX, and NLCACHEM.

          ■    It specifies the size of the LookAhead buffer (specify
               kilobytes).  The LookAhead buffer requires that you allocate
               additional conventional memory to the size of the LookAhead
               buffer.  The LookAhead Buffer is used during sequential disk
               accesses to improve computer performance.  NetWare Lite Cache
               continually monitors your disk activity and turns LookAhead on
               and off according to the type of reads being done.  When you
               are performing sequential reads, NetWare Lite Cache reads large
               blocks of sectors into the LookAhead buffer.  This saves time
               by anticipating future reads and combining them with reads that
               have already been requested.


          ■    The LookAhead buffer size can be from 0 to 16 KB.  Consider a
               LookAhead buffer size of at least 9 KB.  If you specify a
               LookAhead buffer of zero, both LookAhead buffer size (/B) and
               the deferred write capability (/T) are disabled.

     /O        Control Table Location

          ■    Use with NLCACHEX and NLCACHEM.

          ■    It directs NetWare Lite Cache to use cache memory instead of
               conventional memory for the cache control tables.  This means
               that more of your conventional memory is available for other
               applications.

          ■    The /O option is suppressed if either the HMA (High Memory
               Area) beginning at address 1024 KB is not available or if the
               /R options used.

          ■    The /O option may reduce cache performance (speed) when used
               with abnormally slow add-on memory boards.

     /P        Place LookAhead in Expanded Memory

          ■    Use with NLCACHEM.

          ■    Uses expanded memory (instead of conventional memory) for the
               LookAhead buffer.

          ■    The /P option may reduce cache performance (speed) when used
               with abnormally slow add-on memory boards.

     /R        Disable A20 Latch

          ■    Use with NLCACHEX.

          ■    This switch disables the use of CPU latch A20.  Only use this
               option if you have compatibility problems or if your computer
               hangs for no apparent reason.

          ■    The /R option may be selected automatically in some computer
               configurations.

     /S        Assign Cache High

          ■    Use with NLCACHEX.

          ■    It places the cache memory at the top of the extended memory.
               This may be necessary if you are using programs that reallocate
               extended memory, such as Windows/386, AutoCAD, and Lotus 123 -
               release 3.  If you use this option, NetWare Lite Cache ignores
               any starting address specification.

     /T=  Maximum Write Delay

          ■    Use with NLCACHEC, NLCACHEX, and NLCACHEM.

          ■    This switch specifies the maximum delay value for deferred disk
               writes.  The delay value may be from 0 to 5 seconds.  Write
               delay is disabled if you enter a delay value of 0 (/T=0) or if
               the LookAhead buffer is set to 0 (/B=0).  If the maximum write
               delay value is zero or if the LookAhead buffer value is zero,

               NetWare Lite Cache operates as a write-through cache.  The
               deferred write feature speeds up your computer in two ways:

               1.   It groups multiple small-write requests into fewer
                    large-write requests.

               2.   It avoids repetitive writes to the same sectors.  DOS
                    spends much of its time writing and rewriting the same
                    File Attribute Table (FAT) sectors on your disk.  When
                    deferred writes are pending and a new write request is
                    made for the same sectors, the new write data replaces
                    older data so the physical write is performed once with
                    the most recent changes.

     /U        Nonconforming Partition

          ■    Use with NLCACHEC, NLCACHEX, and NLCACHEM.

          ■    Certain schemes for partitioning hard disks larger than 33 MB
               do not handle the disk BIOS interrupts correctly.  If the disk
               BIOS interrupts are handled incorrectly, use the /U option.

          ■    The /U option is not required for normal DOS disk partitions.
               If this option is used, only the first 256 MB of each physical
               disk is cached.

     /V        Disable INT 19 Capture

          ■    Use with NLCACHEC, NLCACHEX, and NLCACHEM.

          ■    This switch disables normal interrupt line 19 capture.  It may
               solve problems with rare and unusual programs that use
               interrupt line 19 in a nonstandard manner.

     /W        Disable Duplicate Write Check

          ■    Use with NLCACHEX and NLCACHEM.

          ■    This switch suppresses duplicate write-checking that NetWare
               Lite Cache normally uses to avoid rewriting cached sectors that
               have not changed.  The checking logic may produce false
               compares when used with abnormally slow add-on memory boards.
               If your computer stops when the cache is started, try using
               this option.

     /X        Disable Memory Diagnostic

          ■    Use with NLCACHEX and NLCACHEM.

          ■    When you start NetWare Lite Cache, it normally performs a brief
               memory diagnostic check.  If you use this option, the memory
               check is skipped.

     /Y        Enable 8088/86 High Memory Transfers

          ■    Use with NLCACHEC and NLCACHEM.

          ■    It enables the caching of disk transfers to or from memory
               addresses above B000:0000 on 8088/8086 computers.  If this
               option is not used when NLCACHEC is running, transfers are not
               cached due to the potential hardware DMA (Direct Memory Access)
               channel unreliability.

     /Z        Disable Snooze Alarm

          ■    Use with NLCACHEC, NLCACHEX, and NLCACHEM.

          ■    This switch disables NetWare Lite Cache's snooze alarm.  The
               snooze alarm generates a low-pitched beep if NetWare Lite Cache
               is unable to find a safe time slot to complete a deferred
               write.  The alarm sounds every 5 seconds until pending deferred
               writes are completed.

     NetWare LITE CACHE CONTROL

     After NetWare Lite Cache is started, you can control its operation by
     executing a cache control command.  The control command consists of the
     name of the caching program and a control option.  For example, if you
     use NLCACHEX and want to get help on NetWare Lite Cache options, type the
     following:

          NLCACHEX /HELP <Enter>

     Cache Control Commands

     /HELP

          ■    Use with NLCACHEC, NLCACHEX, and NLCACHEM.

          ■    This switch displays parameters and options that can be used in
               the cache-startup command line and lists the cache control
               commands.

     /Q   Quit

          ■    Use with NLCACHEC, NLCACHEX, and NLCACHEM.

          ■    If NetWare Lite Cache was started as a TSR from the DOS prompt
               or batch file, this option terminates the NetWare Lite Cache
               program and attempts to release all memory it was using.  If
               other TSR programs were loaded after NetWare Lite Cache,
               NetWare Lite Cache's conventional memory may be locked.  If
               this happens, you may be able to quit NetWare Lite Cache by
               unloading the TSR programs that were loaded after NetWare Lite
               Cache and trying the /Q command again.

          ■    If NetWare Lite Cache was started from your CONFIG.SYS file as
               a device driver, this option has no effect.  Device drivers
               cannot be removed from memory.  The only way to take a device
               driver out of memory is to remove its "device=" statement from
               your CONFIG.SYS file and reboot your computer.

     -    Disable and Flush

          ■    Use with NLCACHEC, NLCACHEX, and NLCACHEM.

          ■    Flushes the cache buffers and disables the cache.  When the
               cache is disabled, hard disk reads and writes are performed as
               if the cache was never loaded.  The cache remains in memory and
               can be enabled with the "+" option.

     +    Enable and Flush

          ■    Use with NLCACHEC, NLCACHEX, and NLCACHEM.

          ■    This switch flushes the cache buffers, resets the cache
               statistics to 0, and enables the cache if it was previously
               disabled with the "-"option.

     ?    Status

          ■    Use with NLCACHEC, NLCACHEX, and NLCACHEM.

          ■    Displays cache status.  The top portion of the status screen
               displays:

               1.   Cache size
               2.   Drives being cached
               3.   Current cache options

          ■    In some cases, NetWare Lite Cache may selectively enable
               certain options, even though these options were not specified
               on the cache startup command.  If the cache has been disabled
               with the "-" option, the screen displays "cache is inactive."
               If "cache is inactive" is followed by an error code, a serious
               problem exists.  An error code 99 indicates that some other
               program is writing into NetWare Lite Cache's control tables.
               Any other error code indicates a problem with your add-on
               memory.

     The Disk Usage Statistics show the following:

     1.   Number of read requests that DOS made
     2.   Number of physical disk reads that were performed
     3.   Percentage of reads saved because the data was in the cache
     4.   Number of write requests that DOS made
     5.   Number of physical disk writes actually performed
     6.   Percentage of disk writes saved because they were duplicated writes
          or the data had not changed

     The Error Statistics show the following:

     1.   Number of cache memory errors
     2.   Number of disk transfer errors
     3.   Number of errors ignored by the user

     Memory Errors are tallied whenever an error is detected in your extended
     or expanded memory subsystem.

     Disk errors are tallied whenever an error is reported by your disk drive
     subsystem.  Errors ignored by users are tallied when a disk error is
     detected while performing a deferred write and a user enters an ignore
     response at the "Retry or Ignore" prompt.

     MEMORY REQUIREMENT

     The resident conventional memory size required by NetWare Lite Cache is
     the total of the following:

  ┌────────────────────┬────────────────┬────────────────┬────────────────┐
  │        SIZES       │    NLCACHEC    │    NLCACHEX    │    NLCACHEM    │
  ├────────────────────┼────────────────┼────────────────┼────────────────┤
  │Cache Program Size  │ 8 KB           │ 8 KB           │ 8 KB           │
  ├────────────────────┼────────────────┼────────────────┼────────────────┤
  │LookAhead Buffer    │ See /B option  │ See /B option  │ Note 1 Below   │
  │Size                │                │                │                │
  ├────────────────────┼────────────────┼────────────────┼────────────────┤
  │Cache Size          │ The amount of  │ Not applicable │ Not applicable │
  │                    │ memory you     │                │                │
  │                    │ allocate to    │                │                │
  │                    │ the cache      │                │                │
  ├────────────────────┼────────────────┼────────────────┼────────────────┤
  │Resident Control    │ Not applicable │ Note 2 and 3   │ Note 2 and 3   │
  │Table Size          │                │ below          │ below          │
  ├────────────────────┴────────────────┴────────────────┴────────────────┤
  │Note 1:  LookAhead buffer size may be controlled with the /B= option.  │
  │         If the /P option is active (see "Cache Startup Commands"),    │
  │         the LookAhead buffer is placed in the EMS memory.  No         │
  │         resident conventional (base) memory is required for the       │
  │         LookAhead Buffer.                                             │
  │                                                                       │
  │Note 2:  If the /O option is active, cache sizes up to 5.3 MB require  │
  │         no resident control table memory.  If your cache size exceeds │
  │         5.3 MB, multiply the cache size in megabytes by four to get   │
  │         the resident control table size in kilobytes.                 │
  │                                                                       │
  │Note 3:  If the /O option is not active, the resident control table    │
  │         requires 12 KB for each megabyte of cache memory.             │
  └───────────────────────────────────────────────────────────────────────┘

     COMPATIBILITY

     NetWare Lite Cache is fully compatible with the XMS protocol, DOS network
     protocols, DesqView, Windows 3.1, and earlier Windows versions, and it
     operates with PC, XT, AT, and PS/2 compatible computers under MS-DOS and
     PC-DOS versions 2 through 5, DR DOS 6.0, and Windows 3.0 and 3.1.

     If you use a "Load High" memory manager such as 386MAX or QEMM, you may
     load the cache high.  Even though this can be done, it may seriously
     impair cache performance when used with abnormally slow add-on memory
     boards.

     ERROR MESSAGES

     General Start-Up Errors

     ■    "Already loaded"
          --   NetWare Lite Cache is already loaded.

     ■    "Amount not numeric"
          --   Invalid size value specified.

     ■    "Data Compare Error at location hhhhh"
          --   hhhhh is a hexadecimal memory address.  An error was detected
               during the memory diagnostic.

     ■    "Invalid command line option"
          --   Improper command line option specified.

     ■    "No compatible fixed disk!"
          --   No compatible disk found.

     ■    "No Extended Memory available"
          --   Either your computer has no extended memory installed, or
               another process is using all the extended memory.

     ■    "A different NLCache is running"
          --   A different version of NetWare Lite Cache caching program is
               already installed.

     ■    "Too many drive letter options!"
          --   You are attempting to cache more drives than allowed.

     ■    "Unsupported sector size!"
          --   NetWare Lite Cache supports only sector between 512 and 16384
               bytes.

     NLCACHEX Specific Start-Up Errors

     ■    "Insufficient Extended Memory"
          --   There is not enough extended memory available to start the
               cache.

     ■    "HMA is not available"
          --   The High Memory Area at location 1024 is in use by another
               program.  The cache control tables will be located in resident
               conventional (base) memory.

     ■    "XMS Error Code\ xx"
          --   xx is an error code returned by the extended memory manager.
               This indicates a serious malfunction in the XMS manager.  The
               most common error codes are the following:

                    80 -- function not implemented
                    81 -- a VDISK device was detected
                    82 -- an A20 error occurred
                    8e -- a general driver error occurred
                    8f -- unrecoverable driver error occurred
                    A0 -- all extended memory is allocated
                    A1 -- all extended memory handles used
                    A2 -- invalid handle
                    A9 -- a parity error occurred

     NLCACHEM Specific Startup Errors

     ■    "Expanded Memory content does not match data as written"
          --   An error was detected during the cache start-up memory
               diagnostics.  You may have a hardware malfunction.

     ■    "Insufficient Expanded Memory free"
          --   All expanded memory is in use by other programs.

     ■    "No Expanded Memory Manager"
          --   Install the expanded memory manager software you received with
               your computer or with your expanded memory board.

     Status Errors

     ■    "Cache is inactive: Error 99 at (location)"
          --   The cache tables have been overwritten by another program that
               is accessing memory outside its allocated region.  This
               condition may be caused by a faulty Terminate-and-Stay Resident
               (TSR) program or by a normal program addressing memory

               out-of-bounds.  You can identify the offender by removing
               programs one at a time until the problem goes away.

     ■    "Cache is inactive:  Error xx"
          --   xx is the error code given by the EMM or LIM driver.  If
               NLCACHEM is unable to save the EMS page map due to repeated
               errors from the EMS driver, the cache shuts down.  There may be
               a serious problem with the EMS board or the EMM driver
               software.

     Errors When Quitting

     ■    "Cannot release resident memory"
          --   Other programs are loaded above NetWare Lite Cache.  You must
               unload these programs before quitting the cache.

     ■    "Cannot remove device driver"
          --   NLCache was loaded as a device that cannot be unloaded with the
               /Q option.

SOLUTION

     NA