NAME

over − optical volume erase (rewritable)

SYNOPSIS

over [−abfnvz] [−l length] [−p pattern] [−q quota] [−s source] od [... od]

DESCRIPTION

over destroys the contents of an erasable optical volume by initializing the POOL and ROOT index blocks.  over should be run on erasable optical volumes before they are mounted.  Otherwise, these volumes may appear to have no available space.  od is a character-special device node referencing the od device driver.  Multiple device names may be specified, and device names may be interleaved with option switches.  Options are effective for all following device names. 

OPTIONS

−a Clear all blocks on the volume.  If this option is not specified, the file system on the volume is inspected and only those blocks actually in use are cleared.  Selecting this option also sets the −f and −z options. 

−b Block — the following value is the initial block number to clear.  The default initial block number is zero. 

−f Force — clear the volume even though it may contain active nodes.  If this option is not specified, the file system is checked to insure it has no active nodes other than its root directory.  If any other active nodes are discovered, the volume is not cleared.  This option is assumed if the −a option is specified. 

−l The following value is the buffer length in blocks.  To optimize access latency, physical data transfers should approximate a multiple of the data transfer limit.  The default buffer length is 248 kilobytes. 

−n the following value is the number of blocks to clear.  The default block count is calculated from the existing space utilization on the volume (unless the −a option is specified) the initial block number and the total number of blocks on the volume. 

−p The following value is the data pattern to record.  The pattern is concatenated with itself if necessary to produce a longword value.  The default data pattern is zero.  Selecting this option also sets the −a option. 

−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. 

−s Source — the following name specifies a device or file containing an optical file system.  Subsequent devices specified will be initialized with a duplicate of this file system, taking account of differences in the number of blocks on each volume.  The physical block sizes on the source volume must be the same as each of the targets.  over will only write to a WORM volume to copy from another WORM volume. 

−v Verbose — Display status and progress messages. 

−z Clear all active blocks on the volume to zero.  If this option is specified, an all-zero pattern is written in active blocks on the volume, allowing the volume to mount in the write-once mode.  Otherwise, only active index blocks on the volume are cleared and an index block is created for the free space pool, allowing the volume to mount in the rewritable mode.  This option is assumed if the −a option is specified. 

EXAMPLES

To clear an empty volume: over /dev/od0

To clear an active volume: over -f /dev/od0

To clear a volume to zero: over -z /dev/od0

SEE ALSO

ofs(4), ofsd(8), ofsck(8), omount(8)

  —  30 November 1994