irix - fstab (4)
NAME
fstab - static information about filesystems
DESCRIPTION
The file /etc/fstab describes the filesystems and swapping partitions
used by the local machine. The system administrator can modify it with a
text editor. It is read by commands that mount, unmount, and check the
consistency of filesystems. The file consists of a number of lines of
the form:
filesystem directory type options frequency pass
For example:
/dev/root / efs rw 0 0
Fields are separated by white space; a `#' as the first non-white space
character indicates a comment.
The entries from this file are accessed using the routines in
getmntent(3), which return a structure of the following form:
struct mntent {
char *mnt_fsname; /* filesystem name */
char *mnt_dir; /* filesystem path prefix */
char *mnt_type; /* e.g. efs, nfs, proc, or ignore */
char *mnt_opts; /* rw, ro, hard, soft, etc. */
int mnt_freq; /* dump frequency, in days */
int mnt_passno; /* parallel fsck pass number */
};
This structure is defined in the <mntent.h> include file. To compile and
link a program that calls getmntent(3), follow the procedures for section
(3Y) routines as described in intro(3).
The mnt_dir field is the full pathname of the directory to be mounted on.
The mnt_type field determines how the mnt_fsname and mnt_opts fields are
interpreted. Here is a list of the filesystem types currently supported,
and the way each of them interprets these fields:
xfs mnt_fsname must be a block special device (for example,
/dev/root) or a logical volume.
efs mnt_fsname must be a block special device (for example,
/dev/root) or a logical volume.
proc mnt_fsname should be the /proc directory. See proc(4).
fd mnt_fsname should be the /dev/fd directory. See fd(4).
nfs mnt_fsname is the path on the server of the directory to be
served. (NFS option only).
cdfs A synonym for type iso9660 (see below). This type is required
for MIPS ABI compliance.
iso9660 mnt_fsname must be a generic SCSI device. These are located in
the directory /dev/scsi (for example, /dev/scsi/sc0d7l0). See
ds(7M). This filesystem type is used to mount CD-ROM discs in
ISO 9660 (with or without Rock Ridge extensions) and High
Sierra formats. eoe2.sw.cdrom must be installed in order to
use the iso9660 filesystem type.
dos mnt_fsname must be a floppy device. These are located in the
directory /dev/rdsk (for example, /dev/rdsk/fds0d2.3.5). See
smfd(7M).
hfs mnt_fsname must be either a floppy device or a generic SCSI
device. Floppy devices are located in the directory /dev/rdsk
(for example, /dev/rdsk/fds0d2.3.5hi). See smfd(7M). SCSI
devices are located in the directory /dev/scsi (for example,
/dev/scsi/sc0d4l0). See ds(7M).
swap mnt_fsname should be the full pathname to the file or block
device to be used as a swap resource.
cachefs mnt_fsname should be the filesystem name for the backing
filesystem to be mounted as a cache filesystem. This will
either be the special filename (for example, /dev/scsi/sc0d7l0)
or host:path.
rawdata mnt_fsname may be the block/char special device of the
partition or logical volume to reserve (mnt_dir is ignored).
This entry enables the system utilities (for example, mkfs,
mount, and so on) to treat the raw partition or logical volume
as 'mounted', preventing the partition from inadvertently being
overwritten. Any packages that require dedicated raw
partitions (databases and so on) should consider placing a
rawdata entry in fstab(4).
If the mnt_type is specified as ignore, then the entry is ignored. This
is useful to show disk partitions not currently used. mnt_freq is not
used in current IRIX systems.
mnt_passno can be used to control the behavior of parallel filesystem
checking on bootup, see fsck(1M).
The mnt_opts field contains a list of comma-separated option words. Some
mnt_opts are valid for all filesystem types, while others apply to a
specific type only.
Options valid on all filesystems (the default is rw) are:
rw Read/write.
ro Read-only.
noauto Ignore this entry during a mount -a command, to allow the
definition of fstab entries for commonly-used filesystems that
should not be automatically mounted.
grpid Causes a file created within the filesystem to have the group
ID of its parent directory, not the creating process's group
ID.
nosuid Setuid execution not allowed for non-superusers. This option
has no effect for the superuser.
nodev Access to character and block special files is disallowed.
Options specific to xfs filesystems are:
dmi Enable the Data Management Interface event callouts.
Options specific to efs filesystems (the default is fsck, noquota) are:
raw=path The filesystem's raw device pathname (for example, /dev/rroot).
fsck fsck(1M) invoked with no filesystem arguments should check this
filesystem.
nofsck fsck(1M) should not check this filesystem by default.
quota Disk quotas enforced.
noquota Disk quotas not enforced.
lbsize=n The number of bytes transferred in each read or synchronous
write operation.
The value assigned to the lbsize option must be a power of two
at least as large as the system page size. This value is
returned by the getpagesize(2) system call and is normally
either 4096 or 16384 depending on the system type. The current
default for lbsize is the largest power of two less than or
equal to the size of one disk track. An invalid size will
cause the mount to fail with the error EINVAL. Note that less
than lbsize bytes will be transferred if there are not lbsize
contiguous bytes of the addressed portion of the file on disk.
Options specific to iso9660 filesystems (the default is rw, which has no
effect since CD-ROM discs are always read-only) are:
setx Set execute permission on every file on the mounted filesystem.
The default is to make an intelligent guess based on the first
few bytes of the file.
notranslate
Don't translate ISO 9660 filenames to UNIX filenames. The
default is to convert upper case to lower case and to truncate
the part including and after the semicolon.
cache=blocks
Set the number of 2048 byte blocks to be used for caching
directory contents. The default is to cache 128 blocks.
noext Ignore Rock Ridge extensions. The default when the noext
option is not specified is to use Rock Ridge extensions if
present.
susp Enable processing of System Use Sharing Protocol extensions to
the ISO 9660 specification. This is the default.
nosusp Disable processing of System Use Sharing Protocol extensions.
This has the same effect as the noext option.
rrip Enable processing of the Rock Ridge extensions. This is the
default.
norrip Disable processing of the Rock Ridge extensions. This is
equivalent to the noext option.
nmconv=[clm]
This option is supplied for MIPS ABI compliance; some non-IRIX
systems may implement it only for type cdfs, IRIX allows it
with type iso9660 also. Only one of the three letters c, l, or
m can be specified. This option controls filename translation.
c has the same meaning as notranslate above. l requests
translation to lower case (the IRIX default), and m suppresses
the version number (also the IRIX default).
NFS clients can mount iso9660, dos, and hfs filesystems remotely by
specifying hostname:mountpoint for filesystem and nfs for type, where an
iso9660, dos, or hfs filesystem is mounted at mountpoint on the host
hostname. In this case, the same options apply as with nfs (see below).
If the NFS option is installed, the following options are valid for nfs
filesystems:
vers=n Use NFS protocol version n. (The default is to try version 3,
falling back to version 2 if the version 3 mount fails.)
bg If the first attempt fails, retry in the background.
fg Retry in foreground. (Default)
retry=n Set number of mount failure retries to n. (Default = 10000)
rsize=n Set read buffer size to n bytes. (Default = 8K)
wsize=n Set write buffer size to n bytes. (Default = 8K)
timeo=n Set NFS timeout to n tenths of a second. (Default = 11)
retrans=n Set number of NFS retransmissions to n. (Default = 5)
port=n Set server UDP port number to n. (Default = 2049)
hard Retry request until server responds. (Default)
soft Return error if server doesn't respond.
intr Allow accesses to be interrupted by the following signals:
SIGHUP, SIGINT, SIGQUIT, SIGKILL, SIGTERM, and SIGTSTP. (This
is ``off'' by default.)
acregmin=t
Set the regular file minimum attribute cache timeout to t
seconds. (Default = 3)
acregmax=t
Set the regular file maximum attribute cache timeout to t
seconds. (Default = 60)
acdirmin=t
Set the directory minimum attribute cache timeout to t seconds.
(Default = 30)
acdirmax=t
Set the directory maximum attribute cache timeout to t seconds.
(Default = 60)
actimeo=t Set regular and directory minimum and maximum attribute cache
timeouts to t seconds.
noac No attribute caching.
private Do not flush delayed writes on last close of an open file, and
use local file and record locking instead of a remote lock
manager.
shortuid Do not let users with userids or groupids larger than 65535
(see id(1M)) create or own files. Some versions of UNIX do not
support large userids; trying to create a file with a large
userid on such an NFS server can produce undefined and
symttl=t Set the time-to-live for symbolic links cached by NFS to t
seconds. symttl=0 turns off NFS symlink caching. The maximum
value for t is 3600. (Default = 3600)
asyncnlm Use asynchronous NLM RPC calls. The default is to use
synchronous NLM. Using this option requires that lockd(1M) be
running.
The bg option causes mount to run in the background if the server's
mountd(1M) does not respond. mount attempts each request retry=n times
before giving up.
Once the filesystem is mounted, each NFS request waits timeo=n tenths of
a second for a response. If no response arrives, the time-out is
multiplied by 2, up to a maximum of MAXTIMO (900), and the request is
retransmitted. When retrans=n retransmissions have been sent with no
reply a soft mounted filesystem returns an error on the request and a
hard mounted filesystem retries the request. Filesystems that are
mounted rw (read-write) should use the hard option. The number of bytes
in a read or write request can be set with the rsize and wsize options.
In the absence of client activity that would invalidate recently acquired
file attributes, NFS holds attributes cached for an interval between
acregmin and acregmax for regular files, and between acdirmin and
acdirmax for directories. The actimeo option sets all attribute timeout
constraints to a given number of seconds. The noac option disables
attribute caching altogether.
The private option greatly improves write performance by caching data and
delaying writes on the assumption that only this client modifies files in
the remote filesystem. It should be used only if the greater risk of
lost delayed-write data in the event of a crash is acceptable given
better performance. EFS uses caching strategies similar to private NFS
The system reduces the risk of data loss for all filesystems by
automatically executing a partial sync(2) at regular intervals.
Options specific to swap resources are:
pri=t Set the priority of the swap device to t. The legal values are
from 0 to 7 inclusive.
swplo=t Set the first 512 byte block to use to t (default is 0).
length=t Set the number of 512 byte blocks to use to t (default is
entire file/partition).
maxlength=t
Set the maximum number of 512 byte blocks to grow the swap area
to t (default is to use length).
vlength=t Set the number of virtual 512 byte blocks to claim this swap
file has to t (default is to use length).
All other options except for noauto are ignored for swap files.
If the CacheFS option is installed, the following options are valid for
cachefs filesystems:
backfstype=file_system_type
The filesystem type of the back filesystem (for example, nfs).
Any of the following filesystem types may be used as the back
filesystem: nfs, nfs3, iso9660, dos, cdfs, kfs, or hfs. If
this option is not specified, the back filesystem type is
determined from the filesystem name. Filesystem names of the
form hostname:path will be assumed to be type nfs.
backpath=path
Specifies where the back filesystem is already mounted. If
this argument is not supplied, CacheFS determines a mount point
for the back filesystem.
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. In the write-around mode, writes are
made to the back filesystem, and the affected file is purged
from the cache. Also in this mode, file and record locking is
performed through the back filesystem. You can use the non-
shared mode (the default) when you are sure that no one else
will be writing to the cached filesystem. In this mode, all
writes are made to both the front and the back filesystem, and
the file remains in the cache.
noconst By default, consistency checking is performed. Disable
consistency checking by specifying noconst only if you mount
the filesystem read-only.
private Causes file and record locking to be performed locally. In
addition, files remain cached when file and record locking is
performed. By default, files are not cached when file and
record locking is performed and all file and record locking is
handled by the back filesystem.
local-access
Causes the front filesystem to interpret the mode bits used for
access checking instead or having the back filesystem verify
purge Purge any cached information for the specified filesystem.
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
filesystem has changed. If it has, all information about the
file is purged from the cache and new data is retrieved from
the back filesystem. 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
filesystem has changed. If it has, all information about the
directory is purged from the cache and new data is retrieved
from the back filesystem. 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.
bg This option causes mount to run in the background if the back
filesystem mount times out.
disconnect
Causes the cache filesystem to operate in disconnected mode
when the back filesystem fails to respond. This causes read
accesses to files already cached to be fulfilled from the front
filesystem even when the back filesystem does not respond.
NOTES
The default fstab contains the following entry for the /usr filesystem:
/dev/usr /usr efs rw,noquota,raw=/dev/rusr 0 0
The setup program MAKEDEV (see MAKEDEV(1M)) creates /dev/usr and
/dev/rusr as links to partition 6 on the root disk. This is the normal
filesystem residing elsewhere (for example, on a second disk or on a
logical volume, described in lv(7M)), the mnt_fsname field must be
changed to the full pathname of the device where the /usr filesystem
actually resides. If present, the path specified by the raw option
should also be changed to the corresponding full pathname. For example:
/dev/dsk/ips0d1s7 /usr efs rw,raw=/dev/rdsk/ips0d1s7 0 0
Note that if this is done, the /dev/usr and /dev/rusr devices created by
MAKEDEV do not point to the device containing the /usr filesystem, and
they should not be referenced.
Caution: Do not attempt to reconfigure a system with /usr in a non-
default volume by manually recreating these /dev/usr and /dev/rusr links
and leaving the fstab entry unchanged. While this works in normal
operation, it leads to incorrect behavior when installing new software.
The filesystem types nfs2, nfs3, and nfs3pref are accepted for
compatibility with earlier releases. nfs2 is equivalent to vers=2. nfs3
is equivalent to vers=3. nfs3pref is equivalent to nfs with no vers=
option.
FILES
/etc/fstab
SEE ALSO
cfsadmin(1M), fsck(1M), fsck_cachefs(1M), mount(1M), quotacheck(1M),
quotaon(1M), swap(1M), getmntent(3), fd(4), mtab(4), proc(4).