Command Reference Guide

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STANDARD Printed by: Nora Chuang [nchuang] STANDARD
/build/1111/BRICK/man1/!!!intro.1
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mediainit(1) mediainit(1)
pathname pathname is the path name to the character (raw) device special file associated with
the device unit or volume that is to be initialized. mediainit aborts if you lack
either read or write permission to the device special file, or if the device is currently
open for any other process. This prevents accidental initialization of the root device or
any mounted volume. mediainit locks the unit or volume being initialized so that
no other processes can access it.
Except for SCSI devices, pathname must be a device special file whose minor number
of the device being initialized has the diagnostic bit set. For device special files with
the diagnostic bit set, the section number is meaningless. The entire device is
accessed.
When a given unit contains multiple volumes as defined by the drive controller, any available unit or
volume associated with that controller can be initialized, independent of other units and volumes that share
the same controller. Thus, you can initialize one unit or volume to any format or interleave factor without
affecting formats or data on companion units or volumes. However, be aware that the entire unit or
volume (as defined by the drive controller) is initialized without considering the possibility that it may be
subdivided into smaller structures by the the operating software. When such structures exist, unexpected
loss of data is possible.
mediainit dominates controller resources and limits access by competing processes to other units or
volumes sharing the same controller. If other simultaneous processes need access to the same controller,
some access degradation can be expected until initialization is complete; especially if you are initializing a
tape cartridge in a drive that shares the root disk controller.
In general, mediainit attempts to carefully check any -f (format option) or -i (interleave options)
supplied, and aborts if an option is out of range or inappropriate for the media being initialized. Specifying
an interleave factor or format option value of 0 has the same effect as not specifying the option at all.
For disks that support interleave factors, the acceptable range is usually 1 (no interleave) through n−1,
where n is the number of sectors per track. Refer to the appropriate device operating manual for recom-
mended values.
If a disk being initialized requires an interleave factor but none is specified,
mediainit provides an
appropriate, though not necessarily optimum default.
When a given device supports format options, the allowable range of interleave factors may be related to
the specified format option. In such instances,
mediainit cannot check the interleave factor if one is
specified.
Notes
Most types of mass storage media must be initialized before they can be used. HP hard disks, flexible disks,
and cartridge tapes require some form of initialization, but 9-track tapes do not. Initialization usually
involves formatting the media, writing and reading test patterns, then sparing any defective blocks.
Depending upon the media and device type, none, some, or all of the initialization process may have been
performed at the factory.
mediainit completes whatever steps are appropriate to prepare the media
for error-free operation.
Most HP hard disks are formatted and exhaustively tested at the factory by use of a process more thorough
but also more time-consuming than appropriate for
mediainit. However, mediainit is still valuable
for ensuring the integrity of the media after factory shipment, formatting with the correct interleave factor,
and sparing any blocks which may have become defective since original factory testing was performed.
HP flexible disks are not usually formatted prior to shipment, so they must undergo the entire initialization
process before they can be used.
When a tape is certified, it is thoroughly tested and defective blocks are spared. mediainit usually
certifies a tape only if it has not been certified previously. If the tape has been previously certified and
spared, mediainit usually reorganizes the tape’s spare block table, retaining any previous spares, and
optimizing their assignment for maximum performance under sequential access. Reorganizing the spare
block table takes only a few seconds, whereas complete certification takes about a half-hour for 150-foot
tapes, and over an hour for 600-foot tapes.
Reorganization of a tape’s spare block table technically renders any existing data undefined, but the data is
not usually destroyed by overwriting. To ensure that old tape data is destroyed, which is useful for secu-
rity, complete tape re-certification can be forced with the -r option.
HP-UX Release 11i: December 2000 − 2 − Section 1−−525
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