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Makefile.depend
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gcache.8
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geom_cache.c
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Editing: gcache.8
.\"- .\" Copyright (c) 2010 Edward Tomasz Napierala .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD$ .\" .Dd January 3, 2010 .Dt GCACHE 8 .Os .Sh NAME .Nm gcache .Nd "control utility for CACHE GEOM class" .Sh SYNOPSIS .Nm .Cm create .Op Fl v .Op Fl b Ar blocksize .Op Fl s Ar size .Ar name .Ar prov .Nm .Cm configure .Op Fl v .Op Fl b Ar blocksize .Op Fl s Ar size .Ar name .Nm .Cm destroy .Op Fl fv .Ar name .Nm .Cm label .Op Fl v .Op Fl b Ar blocksize .Op Fl s Ar size .Ar name .Ar prov .Nm .Cm stop .Op Fl fv .Ar name ... .Nm .Cm clear .Op Fl v .Ar prov ... .Nm .Cm dump .Ar prov ... .Nm .Cm list .Nm .Cm status .Op Fl s Ar name .Nm .Cm load .Op Fl v .Nm .Cm unload .Op Fl v .Sh DESCRIPTION The .Nm utility is used to control GEOM cache, which can speed up read performance by sending fixed size read requests to its consumer. It has been developed to address the problem of a horrible read performance of a 64k blocksize FS residing on a RAID3 array with 8 data components, where a single disk component would only get 8k read requests, thus effectively killing disk performance under high load. .Pp Caching can be configured using two different methods: .Dq manual or .Dq automatic . When using the .Dq manual method, no metadata are stored on the devices, so the cached device has to be configured by hand every time it is needed. The .Dq automatic method uses on-disk metadata to detect devices. Once devices are labeled, they will be automatically detected and configured. .Pp The first argument to .Nm indicates an action to be performed: .Bl -tag -width ".Cm destroy" .It Cm create Cache the given devices with specified .Ar name . This is the .Dq manual method. The kernel module .Pa geom_cache.ko will be loaded if it is not loaded already. .It Cm label Cache the given devices with the specified .Ar name . This is the .Dq automatic method, where metadata are stored in every device's last sector. The kernel module .Pa geom_cache.ko will be loaded if it is not loaded already. .It Cm stop Turn off existing cache device by its .Ar name . This command does not touch on-disk metadata! .It Cm destroy Same as .Cm stop . .It Cm clear Clear metadata on the given devices. .It Cm dump Dump metadata stored on the given devices. .It Cm list See .Xr geom 8 . .It Cm status See .Xr geom 8 . .It Cm load See .Xr geom 8 . .It Cm unload See .Xr geom 8 . .El .Pp Additional options: .Bl -tag -width indent .It Fl f Force the removal of the specified cache device. .It Fl v Be more verbose. .El .Sh SYSCTL VARIABLES The following .Xr sysctl 8 variables can be used to control the behavior of the .Nm CACHE GEOM class. The default value is shown next to each variable. .Bl -tag -width indent .It Va kern.geom.cache.used_hi : No 20 .It Va kern.geom.cache.used_lo : No 5 .It Va kern.geom.cache.idletime : No 5 .It Va kern.geom.cache.timeout : No 10 .It Va kern.geom.cache.enable : No 1 .It Va kern.geom.cache.debug : No 0 Debug level of the .Nm CACHE GEOM class. This can be set to a number between 0 and 3 inclusive. If set to 0 minimal debug information is printed, and if set to 3 the maximum amount of debug information is printed. .El .Sh EXIT STATUS Exit status is 0 on success, and 1 if the command fails. .Sh SEE ALSO .Xr geom 4 , .Xr geom 8 .Sh HISTORY The .Nm utility appeared in .Fx 7.0 . .Sh AUTHORS .An Ruslan Ermilov Aq Mt ru@FreeBSD.org
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