FreeDOS help system (hhstndrd 1.0.8 en)[lbacache]

Command: lbacache

LBACACHE is a hard disk cache program. Improves drive performance. It requires XMS memory, and at least a 386 computer.


To load: LBACACHE [size] [DRV drivelist] [FLOP] [TUNA] [TUNW] [TUNS] When loaded: LBACACHE [INFO] [SYNC] [STOP] [STAT] [ZERO] To get help: LBACACHE HELP|/HELP|/?


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)


For further information see lbacache.txt.


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 ------------------------------------------------------------------------------ Copyright (C) 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.