NAME
mount_cachefs — mount CacheFS file systems
SYNOPSIS
mount -F cachefs
[ generic_options ]
-o backfstype=file_system_type
[ other_cacheFS_options ]
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.
Options
To mount a CacheFS file system, use the generic
mount
command with the
-F
option followed by the argument
cachefs.
The following generic
mount
options are available:
- -m
Mount the file system without making an entry in the
/etc/mnttab
file.
- -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.
- -r
Mount the file system read-only.
The following arguments to the
-o
option are specifically for CacheFS mounts.
Use commas to separate multiple options. Note: the
backfstype
argument must be specified.
- backfstype=file_system_type
The file system type of the back file system (for example,
nfs).
- 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.
- 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.
- 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.
- 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/bin.
demandconst
and
noconst
are mutually exclusive.
- local-access
Causes the front file system to interpret the mode bits
used for access checking instead or having the back file
system verify access permissions. Do not use this argument
with secure NFS .
- purge
Purge any cached information for the specified file system.
- rw | ro
Read-write (default) or read-only.
- suid | nosuid
Allow (default) or disallow set-uid execution.
- 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.
- 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.
- 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.
- 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.
- actimeo=n
Sets
acregmin,
acregmax,
acdirmin,
and
acdirmax
to n.
EXAMPLES
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
AUTHOR
mount_cachefs
was developed by Sun Microsystems, Inc.
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