NAME

omount − mount optical disk file systems

SYNOPSIS

omount −a[cfkuvz] [−h hold] [−l length] [-p pad] [-q quota] [−r [date]] [−t time]
omount [−cfiksuz] [−h hold] [−l length] [-p pad] [-q quota] [−r [date]] [−t time] ofs dir [tag]
omount [−cfiksuz] [−h hold] [−l length] [-p pad] [-q quota] [−r [date]] [−t time] ofs | dir | tag

DESCRIPTION

omount attaches the file system ofs to the file system hierarchy at the directory dir, which must already exist. If dir has any contents prior to the omount operation, these remain hidden until the file system is unmounted.  The file system ofs is a character-special device node referencing the ofs pseudo-device driver (see ofs(4)).  tag is an optional label for the volume.  It should be a single word (or a string enclosed in quotes) not over 15 characters in length.  If present, tag is used to verify the identity of the volume. 

If invoked with only one of ofs, dir or tag, omount searches the file /etc/ofstab (see ofstab(5)) for a matching entry and extracts additional parameters from that entry. 

OPTIONS

−a Attempt to mount all the file systems described in /etc/ofstab.  (In this case, ofs and dir are taken from /etc/ofstab).  Filesystems are not necessarily mounted in the order they appear in /etc/ofstab. 

−c Insure file consistency by flushing file index records to disk when files are closed.  If this option is not specified, index records are held in memory for a time after files are closed to facilitate attribute updates.  If this option is specified, files written by archive programs such as tar (which alter file attributes after files are closed) will have redundant index records. 

−f Mount the volume as a single large file rather than as a file system.  This permits direct read-only access to the entire volume as provided by the raw device driver.  Attempting to access blocks on the volume that have not been recorded will produce an end-of-medium indication. 

−h The following value is the drive hold time in seconds.  To optimize access to resources, the user may limit the length of time each volume may remain active in a drive while other volumes are awaiting access.  Once this period has elapsed, if no updates are pending, the volume may be removed from the drive and placed at the end of the queue of waiting volumes.  If a value of zero is supplied, no hold time limit is imposed.  The default hold time is five minutes. 

−i Invert the byte order of numeric fields when writing index records and directory entries.  This option may be specified to maintain consistency on file systems imported from machines employing a different byte order in numeric values.  It only controls the byte order written; index records and directories recorded in either byte order will always be interpreted correctly. 

−k Keep optical file attributes in a magnetic disk file for rapid access while the volume is not immediately available.  Volumes included in a CFS model should use this option (see cfs(4)).  This option is useful for access by index number only (as appears in a CFS link) since name lookup always entails direct volume access. 

−l The following value is the file buffer length in blocks.  To optimize access latency, physical data transfers to and from the optical storage media are accumulated and performed several blocks at a time.  This parameter may be varied to take optimal advantage of the characteristics of various optical disk drives.  The default buffer length is 96 kilobytes. 

−o The following text comprises a comma-separated string of file system options from this list:

buffer=# Set buffer length in blocks (see −l). 

check Insure file system consistency (see −c). 

date=# Set file system regression time (see −r). 

error=# Set I/O error retry quota (see −q). 

flush=# Set flush time in seconds (see −t). 

hold=# Set hold time in seconds (see −h). 

invert Invert byte order on write (see −i). 

keep Keep attributes in cache file (see −k). 

length=# Set buffer length in blocks (see −l). 

min=# Set free-space padding factor (see −p). 

nodev Suppress device node access (see mount(8)). 

noexec Suppress program execution (see mount(8)). 

nosuid Suppress set-uid execution (see mount(8)). 

pad=# Set free-space padding factor (see −p). 

quota=# Set I/O error retry quota (see −q). 

rw/ro Set read-only or read/write (see mount(8)). 

scan/slow Scan entire volume index (see −s). 

time=# Set flush time in seconds (see −t). 

unload Unload volume when idle (see −u). 

zero Suppress zero/duplicate write (see −z). 

−p The following value is the free space padding allowance in blocks per thousand.  If less than this amount of space remains on the volume, only the super-user may create files.  The default padding allowance is one block per thousand. 

−q The following value is the maximum number of contiguous errors accepted without producing a fatal I/O fault.  If this value is zero, no error quota is imposed.  The default error quota is 24. 

−r Read-only — Mount the specified file system read-only, even if the entry in /etc/ofstab specifies that it is to be mounted read-write.  Physically write-protected volumes are always mounted read-only, whether or not this option is specified. 

The following value, if supplied, represents a time in the past to which the file system should regress.  All files and directories on the volume will appear exactly as they were at that instant in time.  More recent files and changes will disappear, and deleted or altered files will be restored to their previous state.  The regression time is specified as a single number in any of the forms DD, MMDD, MMDDYY, MMDDhhmm or MMDDYYhhmm, where YY, MM and DD represent the year, month and day, respectively, and hh and mm represent the hour and minute.  An initial zero may be omitted.  If the month or year is not specified, the most recent matching date is selected.  If the hour or minute is not specified, zero is assumed. 

−s Slow mount — Examine every file index record while mounting a file system.  The normal fast-mount sequence locates file index records using an index map.  If any record cannot be read, the corresponding file cannot be accessed.  Using the slow-mount option allows a previous version of such a file index record to be located. 

−t The following value is the buffer flush time in seconds.  Due to the write-once nature of optical file storage media, the OFS daemon attempts to maximize media utilization by keeping recent updates to a file in memory until the file is closed or flushed.  However, to minimize memory usage and to insure that files remain reasonably current, a memory residence time limit is observed.  If no access occurs to a file on the file system within this time, any pending updates will be posted to the optical medium and the memory buffer space occupied will be released for other uses.  The default value of this parameter is one minute.  If a value of zero is supplied, no time limit is imposed, and file updates may remain pending indefinitely, or until the file system is demounted. 

−u Unload this volume to storage whenever it becomes idle.  This serves to optimize access to subsequent volumes. 

−v Verbose — Display a message indicating the file system being mounted. 

−z Conserve space by not replacing regions with identical contents, and by representing empty (zero) regions as gaps in the file index map, since such gaps appear as empty regions when retrieved.  Checking for identical regions entails reading before writing, which imposes a performance penalty unless the file index map is erased (by opening with the TRUNCATE option) before writing. 

Note: The default values stated are initial defaults, which may be altered by option parameters passed to the OFS daemon on initiation (see ofsd(8)).  When a file system mounted with any of these options is demounted, the default values set by the OFS daemon are restored. 

EXAMPLES

To mount a volume read-write:
omount /dev/of0 /od

To mount a volume read-only: omount −r /dev/of0 /od

To specify the flush time: omount −t60 /dev/of0 /od

To select the buffer size: omount −l40 /dev/of0 /od

To set a regression date: omount −r930 /dev/of0 /od

To select dir from ofstab: omount /dev/of0

To select ofs from ofstab: omount /od

To mount all ofs volumes: omount -a

FILES

/etc/ofstab
table of optical file systems

SEE ALSO

ofs(4), ofstab(5), ofsd(8), mount(8), umount(8)

BUGS

Filesystem label validation is not yet implemented. 

If the directory on which a file system is to be mounted is specified by a symbolic link, the file system is mounted on the directory to which the symbolic link refers, rather than being mounted on top of the symbolic link itself. 

  —  30 September 1992