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fscache - manages SmartIO file system caching




fscache advise {pin [-o load] |unpin} [-r] {file1|dir1} [file2|dir2...]

fscache create [-o noauto] special

fscache disable [-o purge] mount_point

fscache enable mount_point

fscache flush [-r] {file1|dir1} [file2|dir2...]

fscache grow -b newsize devpath

fscache info [-q]

fscache list [-r] [devpath|mount_point1|file1|dir1] [devpath|mount_point2|file2|dir2...]

fscache load [-r] [-o sync] {file1|dir1} [file2|dir2...]

fscache offline [-o checkwb] devpath

fscache online [-o noauto] devpath

fscache purge [-o force] {mount_point|fsuuid}

fscache restore-access {mount_point}|file|dir}

fscache set [-r] mode=[nocache|read|writeback] {file1|dir1} [file2|dir2...]

fscache set {writeback_size=newsize|writeback_interval=sec}

fscache stat [-l] [-c] [mount_point]


The fscache command manages SmartIO file system caching for Solid State Drive (SSD) devices. The sfcache command calls the fscache command. You should use the sfcache command directly. Caching is not supported for a read-only file system.

Cluster File System Issues

No cluster issues; command operates the same on cluster file systems.


advise Adds advisories for the heuristic engine to use when making cache population or eviction decisions. Advisories are inherited through each level allowing for coarse or fine grain cache control.
create Create a SmartIO cache.
  Stops caching for the specified mount point. The cache area can be manually added back later. Disabling a mount point is per node, and not cluster-wide. Use the purge flag to remove the cached data from the device.
enable Starts caching for the specified data object.
flush Flushes any writeback data for this file system or file.
grow Increases the size of the cache to the specified size.
info Displays information about a cache area, if one is online. If the -q option is specified, the command returns success if a cache is online but displays no output.
list Displays the cached file systems and their cache usage. Specify one or more files or directories to list the cache status, including any user-specified pinning and mode.
load Loads the specified objects into the file system cache.
  Stops VxFS from using a cache area.
online Explicitly makes a cache area available. The device discovery and notification automatically makes the cache area available. By default, the SF cache is brought online after a reboot. The explicit command allows control at the file system level, if required. If you specify the noauto option, SmartIO only caches the files, directories or mount points for which caching is explicitly enabled.
purge Removes the cached contents for the specified file system. This command frees up dead space in the cache.
  Enables access to files that are missing writeback data. If the writeback cache data could not be flushed to the disk for some files due to an error, SmartIO blocks access to the files. This command only restores access to the files, but it does not restore the missing data.
set mode
  Sets the caching mode, which can be one of the following:
read In this mode, application reads are satisfied from the cache whenever possible. As the file is being accessed, the file system can load data from the disk into the cache. Application writes go to the disk in the usual way. With each write, the file system synchronizes the cache to ensure that applications never see stale data. If a cache device fails, a file cached in read mode is completely present on the disk.
  In this mode, an application write returns success only after the data has been written to the cache. The data is written to the disk at a later time. This mode gives good performance for writes, but also means that the disk copy is not always up to date. Reads are satisfied from the cache if possible, and the file system transparently loads file data into the cache. If a cache device fails, a file cached in writeback mode is not completely present on the disk. If there is a replica cache, the file system uses that replica to find the latest data and write it to the disk. If there is no replica, the disk copy of the file can be incomplete or stale.
  No caching will be performed.
set {writeback_interval|writeback_size}
  Sets the parameters for writeback caching, as follows:
  Specifies how long the dirty data migh remain unflushed. The default is 10 seconds.
  Configures a maximum size for the amount of data in the cache. By default, there is no maximum size. If you set a maximum, allow 512MB for each file system. For a cluster file system, the maximum does not include reflection.
stat Displays the cache statistics for the specified object.


-c Clears the statistics.
-o sync Specifies that data is loaded in the cache synchronously, rather than in the background.
-o load Loads the cache.
-r Recursively process directories and subdirectories.


To start caching for a mount point:

# fscache enable /mnt1

To pin a file in the cache:

# fscache advise pin myfile



Storage Foundation and High Availability Solutions SmartIO for Solid State Devices Solutions Guide

VxFS 7.4 fscache(1M)