scsimgr_estape.7 (2011 09)

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scsimgr_estape(7) scsimgr_estape(7)
Compression Algorithm to use
Default: 0
0x00 = Compression Disabled
0xDEF = default for drive
other = a valid compression value for the
Data Compression Mode Page (0x0F).
best_compression RW uint32
The type of device a particular LUN is
associated with.
Default: 0
Values:
0 = unknown,
5 = HPIB 9-track
6 = DDS1
7 = All other DDS/DAT
8 = Scsi 9-track
9 = QIC
10 = 8mm
11 = IBM 3480, STK 9XXX, STK T10000
12 = Quantum DLT
13 = Sony AIT
14 = IBM 3590
15=LTO
mt_type RW uint32
I/O Load Balancing and Multi-Pathing Policies
The estape driver uses path_lockdown
method as load balancing policy and has minimal support for
multi-pathing.
When the device is first opened after a system boot, a path is chosen and will remain fixed. If the path
fails, the new path will be picked on next open only. But with the support of the
lpt_to_lockdown
attribute beginning in the HP-UX 11i v3 March 2009 Update, it lets users select a lunpath among avail-
able lunpaths to the device, which will be locked down and I/O’s will be issued on the newly selected lun-
path.
Refer to the
scsimgr attribute table in scsimgr(1M) for more information on the lpt_to_lockdown
attribute.
Block Size Limitation for Backup/Restore Applications
The block size in HP-UX 11i v3 SCSI
estape driver is the physical block size on the tape. The
estape
driver gets this block size from the Mass Storage Stack. The actual block size is determined as the smal-
lest value of escsi_maxphys
attribute and the maximum I/O sizes reported by interface drivers on
LUN paths of the LUN.
For more details on
escsi_maxphys
, refer to scsimgr(1M).
To know about the maximum I/O size supported by the card, refer to the technical specifications of the I/O
card.
Warning: Applications that use block size greater than this negotiated value to issue writes will have
their writes broken down by the
estape driver to the actual block size and then written on to the tape.
This step of breaking down a single block to multiple blocks of smaller block size may lead to inconsisten-
cies during some of the tape operations. For example, an application positioning on tape and using the
original application block size might lose track of its correct position assuming it had no visibility of the
actual block size. Also READ operations by an unaware application would be at the incorrect block size.
Application designers/developers are highly encouraged to consider this limitation and ensure that the
block size used is less than or equal to the actual value of the block size.
EXAMPLES
To display scsimgr estape plug-in general help and supported commands:
scsimgr -h -d estape
To get estape driver global statistics:
scsimgr get_stat -d estape
4 Hewlett-Packard Company − 4 − HP-UX 11i Version 3: September 2011