man mount cache fs

mercredi 17 septembre 2008
par  Jerome ROBERT
popularité : 5%

System Administration Commands			mount_cachefs(1M)

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 infor-
mation regarding back file systems, refer to the System
Administration Guide : Basic Administration.

OPTIONS
To mount a CacheFS file system, use the generic mount com-
mand 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 per-
missions. 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.

ro | rw
Read-only or read-write (default).

suid | nosuid
Allow (default) or disallow setuid execution.

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
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

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.


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