Command: lbacache
LBACACHE is a hard disk cache program. Improves drive performance.
It requires XMS memory, and at least a 386 computer.
Syntax:
To load: LBACACHE [size] [DRV drivelist] [FLOP] [TUNA] [TUNW]
[TUNS]
When loaded: LBACACHE [INFO] [SYNC] [STOP] [STAT] [ZERO]
To get help: LBACACHE HELP|/HELP|/?
Options:
size Specifies the buffer size. Default: 2048k. If 1-2 digits, unit
is 256k (in XMS), so default is to use 2 MB XMS. If > 2 digits,
unit is simply 1 kilobyte. Example: 'LBACACHE 8192'. Other
possible syntax: "BUF size" instead of "size".
FLOP Enable the floppy cache (A: and B:, autodetected). To speed up
floppy use, load TICKLE, too! Please report if FLOP has bugs.
A bug can e.g. mean that the cache makes wrong assumptions on
floppy geometry which can lead to data corruption on the disk
or in files copied from disk. If you only use 1.44 MB disks
in an 1.44 MB drive, bugs are extremely unlikely, though...
DRV list Selects which harddisks are cached. No discs are cached by
using the keyword NULL.
It is strongly recommended to let LBAcache autodetect all
cacheable harddisks instead of using this option!
List consists of digits in 0..7, for BIOS drives 80h+x. E.g.:
023 caches BIOS drives 80h, 82h, 83h - first, third and
fourth harddisk (hda, hdc, hdd in Linux terminology).
Important: First BIOS harddisk means ALL drive letters which
are on the first physical harddisk.
TUNA Fully associative cache: Search whole cache for a sector or
for free space in worst case. Slower for big caches but can
give more cache hits than the new (6/2004) default of searching
only up to N (current setting: 16) cache elements (current size
of an element: 8kB).
First tests suggest: slightly more cache hits but lower speed!
TUNW Allocate on write: When data is written to disk, store a copy
in cache, EVEN if that means allocating new space in cache, in
anticipation of reading the data back later. Was the default
until 7/2004. Makes writes "consume" more cache, but is useful
for tasks which work with temp files a lot. If data was cached
anyway, the copy in cache is updated regardless of this option.
TUNS Allocate 320 bytes of low DOS RAM for stacks (new 7/2004). Use
this option if you want to load LBAcache into JEMM386's UMB or
otherwise "not very DMA friendly UMB" and have a SCSI system.
SCSI BIOSes seem to use DMA to stack for geometry check calls!
Note that this memory is *not* freed by LBAcache STOP, as the
unloading protocol would have to be changed too much for that.
NON-LOAD options:
INFO Shows cache statistics and details about resident LBAcaches.
Useful for debugging purposes, but somehow hard to understand.
STAT Shows easier to understand cache statistics only.
ZERO Reset the cache statistics counters to zero.
SYNC Synchronizes all running LBAcache buffers for all drives. As
LBAcache never delays writes, SYNC is just forget cached data.
This is done by calling int 13.46 (BIOS disk: eject) for all
cacheable drives (0, 1, 0x80 .. 0x87). It is recommeded to do
LBACACHE ZERO after LBACACHE SYNC, will make the statistics
more intuitive to read.
STOP Shuts down all running LBAcache instances and frees the XMS
and DOS RAM which they had allocated (removes them from RAM).
If the interrupt chain cannot be restored, LBAcache instances
are left in DOS RAM, but at a reduced size of < 500 bytes.
The XMS memory is always freed. When a single LBAcache is
loaded as last disk related resident program, complete unload
should work most of the time. When loading several LBAcache
instances, often only the last instance can be fully unloaded.
COOL Puts the cache into "cool" mode: accessed sectors are frozen
into the cache (as much as possible - use TUNA to enhance the
effect). See the BINSEL explanations to find out whether this
experimental (9/2004) mode is useful for you.
WARM Puts the cache into "melt" mode: accessed sectors are
unfrozen (defrosted? :-)) from the cache. See above. (9/2004)
Note: WARM, COOL and TEMP all display a diagnostic status
value for debugging, e.g. the current "locked element count".
After that, the normal STAT output is shown.
TEMP Restores the cache to "normal temperature" mode: The frozen-
ness state of the current contents is preserved as far as
possible (if the cache gets really full, things will melt).
Now you have reserved part of the cache for frozen / locked
data and the rest of the cache space in classic mode. (9/2004)
Comments:
For further information see lbacache.txt.
Examples:
In CONFIG.SYS / FDCONFIG.SYS:
INSTALL=LBACACHE.COM [arguments]
or
INSTALLHIGH=LBACACHE.COM [arguments]
or from command line or AUTOEXEC.BAT:
LBACACHE [arguments]
or
LOADHIGH LBACACHE.COM [arguments]
LBACACHE Just running the command without options will
read cache all your hard disks (if available
through the BIOS) with the default cache buffer
size.
LBACACHE buf 20 flop This will read cache all hard disks and floppy
disks, with 5MB of memory for the cache buffer.
LBACACHE info Shows information about your caches.
See also:
cdrcache.sys
(fdxms)
(fdxms286)
(himem)
himemx
jemmex
tickle
xmgr
File:
Please read this command's lsm file also.
You will find the updated version (internet) here and
the version described in this manual page here.
The lsm file contains information about the name of the programmer,
the download site, and some other command related information.
Copyright © 2004 Robert Platt, updated 2011 by W. Spiegl.
This file is derived from the FreeDOS Spec Command HOWTO.
See the file H2Cpying for copying conditions.