gcache(8) [freebsd man page]
GCACHE(8) BSD System Manager's Manual GCACHE(8) NAME
gcache -- control utility for CACHE GEOM class SYNOPSIS
gcache create [-v] [-b blocksize] [-s size] name prov gcache configure [-v] [-b blocksize] [-s size] name gcache destroy [-fv] name gcache label [-v] [-b blocksize] [-s size] name prov gcache stop [-fv] name ... gcache clear [-v] prov ... gcache dump prov ... gcache list gcache status [-s name] gcache load [-v] gcache unload [-v] DESCRIPTION
The gcache 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 com- ponents, where a single disk component would only get 8k read requests, thus effectively killing disk performance under high load. Caching can be configured using two different methods: ``manual'' or ``automatic''. When using the ``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 ``automatic'' method uses on-disk metadata to detect devices. Once devices are labeled, they will be automatically detected and configured. The first argument to gcache indicates an action to be performed: create Cache the given devices with specified name. This is the ``manual'' method. The kernel module geom_cache.ko will be loaded if it is not loaded already. label Cache the given devices with the specified name. This is the ``automatic'' method, where metadata are stored in every device's last sector. The kernel module geom_cache.ko will be loaded if it is not loaded already. stop Turn off existing cache device by its name. This command does not touch on-disk metadata! destroy Same as stop. clear Clear metadata on the given devices. dump Dump metadata stored on the given devices. list See geom(8). status See geom(8). load See geom(8). unload See geom(8). Additional options: -f Force the removal of the specified cache device. -v Be more verbose. SYSCTL VARIABLES
The following sysctl(8) variables can be used to control the behavior of the CACHE GEOM class. The default value is shown next to each vari- able. kern.geom.cache.used_hi: 20 kern.geom.cache.used_lo: 5 kern.geom.cache.idletime: 5 kern.geom.cache.timeout: 10 kern.geom.cache.enable: 1 kern.geom.cache.debug: 0 Debug level of the 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. EXIT STATUS
Exit status is 0 on success, and 1 if the command fails. SEE ALSO
geom(4), geom(8) HISTORY
The gcache utility appeared in FreeBSD 7.0. AUTHORS
Ruslan Ermilov <ru@FreeBSD.org> BSD
January 3, 2010 BSD
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GSTRIPE(8) BSD System Manager's Manual GSTRIPE(8) NAME
gstripe -- control utility for striped devices SYNOPSIS
gstripe create [-v] [-s stripesize] name prov prov ... gstripe destroy [-fv] name ... gstripe label [-hv] [-s stripesize] name prov prov ... gstripe stop [-fv] name ... gstripe clear [-v] prov ... gstripe dump prov ... gstripe list gstripe status gstripe load gstripe unload DESCRIPTION
The gstripe utility is used for setting up a stripe on two or more disks. The striped device can be configured using two different methods: ``manual'' or ``automatic''. When using the ``manual'' method, no metadata are stored on the devices, so the striped device has to be con- figured by hand every time it is needed. The ``automatic'' method uses on-disk metadata to detect devices. Once devices are labeled, they will be automatically detected and configured. The first argument to gstripe indicates an action to be performed: create Set up a striped device from the given devices with specified name. This is the ``manual'' method and the stripe will not exist after a reboot (see DESCRIPTION above). The kernel module geom_stripe.ko will be loaded if it is not loaded already. label Set up a striped device from the given devices with the specified name. This is the ``automatic'' method, where metadata are stored in every device's last sector. The kernel module geom_stripe.ko will be loaded if it is not loaded already. stop Turn off an existing striped device by its name. This command does not touch on-disk metadata! destroy Same as stop. clear Clear metadata on the given devices. dump Dump metadata stored on the given devices. list See geom(8). status See geom(8). load See geom(8). unload See geom(8). Additional options: -f Force the removal of the specified striped device. -h Hardcode providers' names in metadata. -s stripesize Specifies size of stripe block in bytes. The stripesize must be a multiple of the largest sector size of all the providers. -v Be more verbose. SYSCTL VARIABLES
The following sysctl(8) variables can be used to control the behavior of the STRIPE GEOM class. The default value is shown next to each variable. kern.geom.stripe.debug: 0 Debug level of the STRIPE 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. kern.geom.stripe.fast: 0 If set to a non-zero value enable ``fast mode'' instead of the normal ``economic mode''. Compared to ``economic mode'', ``fast mode'' uses more memory, but it is much faster for smaller stripe sizes. If enough memory cannot be allocated, STRIPE will fall back to ``economic mode''. kern.geom.stripe.maxmem: 13107200 Maximum amount of memory that can be consumed by ``fast mode'' (in bytes). This sysctl(8) variable is read-only and can only be set as a tunable in loader.conf(5). kern.geom.stripe.fast_failed A count of how many times ``fast mode'' has failed due to an insufficient amount of memory. If this value is large, you should con- sider increasing the kern.geom.stripe.maxmem value. EXIT STATUS
Exit status is 0 on success, and 1 if the command fails. EXAMPLES
The following example shows how to set up a striped device from four disks with a 128KB stripe size for automatic configuration, create a file system on it, and mount it: gstripe label -v -s 131072 data /dev/da0 /dev/da1 /dev/da2 /dev/da3 newfs /dev/stripe/data mount /dev/stripe/data /mnt [...] umount /mnt gstripe stop data gstripe unload COMPATIBILITY
The gstripe interleave is in number of bytes, unlike ccdconfig(8) which use the number of sectors. A ccdconfig(8) ileave of '128' is 64 KB (128 512B sectors). The same stripe interleave would be specified as '65536' for gstripe. SEE ALSO
geom(4), loader.conf(5), ccdconfig(8), geom(8), gvinum(8), mount(8), newfs(8), sysctl(8), umount(8) HISTORY
The gstripe utility appeared in FreeBSD 5.3. AUTHORS
Pawel Jakub Dawidek <pjd@FreeBSD.org> BSD
May 21, 2004 BSD