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.TH "FLASHCACHE" "7" "September 2011" "flashcache" ""
.hy
.SH NAME
.PP
flashcache \- overview of operation
.SH SYNOPSIS
.PP
modprobe flashcache
.PP
Flashcache consists of a kernel module and userspace utilities.
The module is named "flashcache".
The kernel module can be controlled with \f[I]flashcache_create\f[](8),
\f[I]flashcache_load\f[](8) and \f[I]flashcache_destroy\f[](8)
utilities.
.SH DESCRIPTION
.PP
Flashcache is a block cache for Linux, built as a kernel module, using
the device mapper.
Flashcache supports \f[B]writeback\f[], \f[B]writethrough\f[] and
\f[B]writearound\f[] caching modes.
See \f[I]flashcache_create\f[](8) for a description of caching modes.
.PP
Flascache allows one to use a fast block device such as Solid State
Drives (SSD) as cache to accelerate a slower drive used as backstore.
.PP
Originally, Flashcache was built as a block device cache for I/O
intensive database applications, for example to run an accelerated
InnoDB store for \f[I]mysqld\f[](8), but it can be used as general
purpose backend for filesystems as well.
.SH USAGE
.PP
Before using Flashcache, it might be a good idea to check if device
mapper works properly.
Assuming the partition /dev/md0p1 shall be used as flash cache, one may
try to create a linear device with following command:
.PP
\f[B]echo 0 1024 linear /dev/md0p1 0 | dmsetup create tmpdisk\f[]
.PP
It this works, \f[I]flashcache_create\f[] should be able to create its
device.
.PP
Remove tmpdisk with command:
.PP
\f[B]dmsetup remove tmpdisk\f[]
.PP
Before creating a flashcache device using the \f[I]flashcache_create\f[]
command, the deivce must not be mounted.
.SH SEE ALSO
.PP
\f[C]flashcache_create\f[](8), \f[C]flashcache_load\f[](8),
\f[C]flashcache_destroy\f[](8)
.PP
\f[I]README\f[] and other documents in
\f[B]/usr/share/doc/flashcache\-utils\f[].
In particular, see \f[B]flashcache\-sa\-guide.txt\f[] for configuring
the flashcache kernel module through its \f[I]/proc\f[] interface.
.PP
The flashcache source code and all documentation may be downloaded from
<https://github.com/facebook/flashcache/>.
.SH AUTHORS
.PP
Flashcache is developed by Mohan Srinivasan <mohan@fb.com>
.PP
This man page was written by Dmitry Smirnov <onlyjob@member.fsf.org> for
Debian GNU/Linux (but may be used by others).