Computer Drive User Manual

For IRIX systems, SCSI attached tape drives are typically referred to by pathnames of the form /dev/rmt/
tpsXdYns, where X is the SCSI controller number, and Y is the SCSI ID of the drive. Note that for Ampex
DST drives, the tpsXdYnrns name should be used (indicating that the driver should not attempt to rewind
the drive upon close). For other drives on IRIX, the tpsXdYnsvc name should be used (indicating that the
driver allows compression and variable block sizes).
For Solaris systems, SCSI attached tape drives are typically referred to by pathnames of the form
/dev/rmt/Xc, where X begins at zero and is incremented for each tape drive detected (the ‘c’ indicates
that compression is enabled). In particular note that the device that contains a ‘b’ in the name should
NOT be used, as this will change the behavior of the drive and cause the HPSS Mover to fail.
For Linux systems, this is the name that will be used to provide access to the SCSI raw device. The
pathname will be in the form /dev/raw/rawX, where X specifies the raw device number. You can run the
“raw -q -a” command to determine the correct raw device mappings. SCSI tape devices are referred to
by pathnames of the form /dev/stX, where X begins at zero and is incremented for each LUN detected.
Media Block Size (disk only). The block size for the device. This value should be a multiple of the
underlying disk block size; otherwise an error will occur at first I/O.
Bytes on Device (disk only). The size of the device in bytes.
Advice - The storage class to which this drive will be assigned must have a PV Size less than or equal to
this value.
If the Starting Offset is non-zero, then the Bytes on Device value cannot be greater than the actual size of
the underlying device less the Starting Offset value.
If this value is modified after the disk has been imported into HPSS, it must be emptied, exported and re-
imported.
Starting Offset (disk only). The offset in bytes from the beginning of the disk logical volume at which
the Mover will begin using the volume. The space preceding the offset will not be used by HPSS. This
value should be a multiple of the Media Block Size.
Advice - In some cases, the operating system may maintain control information at the beginning of a disk
volume which should not be overwritten by HPSS. As a specific example, the AIX Logical Volume
Manager (LVM) currently writes a control block at the start of a logical volume that is required during
some operations on mirrored logical volumes (such as splitting the mirror in the case of a failing
physical disk). The Starting Offset field can be used to force the Mover to skip over that control block
before writing the HPSS volume label or any user data (consult AIX documentation to determine the size
of the LVM control block).
SAN ID (disk only). The ID for the SAN group. A group is a set of devices that are logically related,
with the primary characteristic being that all devices in group are accessible by all clients. Each group is
identified with this globally unique group id. It is assigned to all devices within a SAN group.
Device Flags. The following fields are the device flags used by the Mover.
• Read Enabled. An indication of whether the device is available for reading.
• Write Enabled. An indication of whether the device is available for writing.
• Locate Support (tape only). An indication of whether the device supports a high speed (absolute)
positioning operation.
HPSS Management Guide November 2009
Release 7.3 (Revision 1.0) 199