mount_cachefs(1M)

Name | Synopsis | Description | Options | Examples | Attributes | See Also | Bugs

Name

mount_cachefs– mount CacheFS file systems

Synopsis

mount -F cachefs [generic_options] -o backfstype=file_system_type 
     [specific_options] 
     [-O] special mount_point

Description

The CacheFS-specific version of the mount command mounts a cached file system; if necessary, it NFS-mounts its back file system. It also provides a number of CacheFS-specific options for controlling the caching process. For more information regarding back file systems, refer to the System Administration Guide: Basic Administration.

mount_cachefs cannot be used with replicated NFS mounts. mount_cachefs creates a pass through when used with an NFS version 4 mount. No caching is performed.

Options

To mount a CacheFS file system, use the generic mount command with the -F option followed by the argument cachefs.

See mount(1M) for a list of supported generic_options.

-o specific_options

Specify CacheFS file system specific options in a comma-separated list with no intervening spaces.

acdirmax=n

Specifies that cached attributes are held for no more than n seconds after directory update. After n seconds, all directory information is purged from the cache. The default value is 30 seconds.

acdirmin=n

Specifies that cached attributes are held for at least n seconds after directory update. After n seconds, CacheFS checks to see if the directory modification time on the back file system has changed. If it has, all information about the directory is purged from the cache and new data is retrieved from the back file system. The default value is 30 seconds.

acregmax=n

Specifies that cached attributes are held for no more than n seconds after file modification. After n seconds, all file information is purged from the cache. The default value is 30 seconds.

acregmin=n

Specifies that cached attributes are held for at least n seconds after file modification. After n seconds, CacheFS checks to see if the file modification time on the back file system has changed. If it has, all information about the file is purged from the cache and new data is retrieved from the back file system. The default value is 30 seconds.

actimeo=n

Sets acregmin, acregmax, acdirmin, and acdirmax to n.

backfstype=file_system_type

The file system type of the back file system (can be nfs or hsfs).

backpath=path

Specifies where the back file system is already mounted. If this argument is not supplied, CacheFS determines a mount point for the back file system. The back file system must be read-only.

cachedir=directory

The name of the cache directory.

cacheid=ID

ID is a string specifying a particular instance of a cache. If you do not specify a cache ID, CacheFS will construct one.

demandconst

Verifies cache consistency only when explicitly requested, rather than the periodic checking that is done by default. A consistency check is requested by using the -s option of the cfsadmin(1M) command. This option is useful for back file systems that change infrequently, for example, /usr/openwin. demandconst and noconst are mutually exclusive.

local-access

Causes the front file system to interpret the mode bits used for access checking instead of having the back file system verify access permissions. Do not use this argument with secure NFS.

noconst

Disables cache consistency checking. By default, periodic consistency checking is enabled. Specify noconst only when you know that the back file system will not be modified. Trying to perform cache consistency check using cfsadmin -s will result in error. demandconst and noconst are mutually exclusive.

write-around | non-shared

Write modes for CacheFS. The write-around mode (the default) handles writes the same as NFS does; that is, writes are made to the back file system, and the affected file is purged from the cache. You can use the non-shared mode when you are sure that no one else will be writing to the cached file system. In this mode, all writes are made to both the front and the back file system, and the file remains in the cache.

-O

Overlay mount. Allows the filesystem to be mounted over an existing mount point, making the underlying filesystem inaccessible. If a mount is attempted on a pre-existing mount point without setting this flag, mount will fail with the error: mount -F cachefs: mount failed Device busy.

Examples

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Example 1 CacheFS-mounting a File System




The following example CacheFS-mounts the file system server1:/user2, which is already NFS-mounted on /usr/abc as /xyz.

example# mount -F cachefs -o backfstype=nfs,backpath=/usr/abc, cachedir=/cache1 server1:/user2 /xyz

The lines similar to the following appear in the /etc/mnttab file after the mount command is executed:

server1:/user2 /usr/abc nfs /usr/abc /cache1/xyz cachefs backfstype=nfs

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Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Availability	SUNWcsu

See Also

cfsadmin(1M), fsck_cachefs(1M), mount(1M), attributes(5) System Administration Guide: Basic Administration

Bugs

The output for the generic_option -p output is incorrect for cachefs.

SunOS 5.11  Last Revised 18 Mar 2004

Name | Synopsis | Description | Options | Examples | Attributes | See Also | Bugs