Networker General Guidelines - HP 12000 Design Manual

Networker General Guidelines

The following NetWorker guidelines apply to a VLS regardless of whether deduplication is enabled
or disabled:
Tape block size: Set the tape block size to 256 KB (maximum supported size, 512KB is not
supported). Otherwise, NetWorker uses a block size based on the device type used. For
example, LTO-2 is set by EMC to 64 KB, assuming that the operating system is configured for
variable block size mode. You can experience metadata errors when setting a fixed block
size on your initiator if the block size in the stinit.def file does not match the NetWorker
block size, so set a fixed block size on your initiator in the stinit.def file that matches the
NetWorker block size. Use the full number in the stinit.def file with a lowercase "k."
Disable multiplexing: Even though multiplexing is supported, HP does not recommend it for
virtual libraries because the performance impact on restores and deduplication. Because you
can create additional drives easily in the virtual library and allocate them to Storage Nodes
as necessary, sufficient backup streams can be concurrently written without requiring
multiplexing. To disable multiplexing, do one of the following:
Default pool: Set the NetWorker device "target sessions" for any virtual tape library tape
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drives that will be used by the Default pool to 1.
◦ All other pools: Set the pool "parallelism" parameter to 1, which enforces one stream
per virtual tape library tape drive when writing to a pool configured with this parameter.
HP recommends using a non-default pool with the virtual tape library with the "parallelism"
parameter, because NetWorker autochanger reconfigurations may delete and recreate
devices, and resetting the "target sessions" parameter to the default of 4.
Windows device configuration: The following guidelines apply to Networker on Windows:
Disable Plug and Play Test Unit Ready (TUR) for any tape drivers in use. A SCSI TUR
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command may rewind a mounted NetWorker tape unexpectedly, causing data loss.
Enable "verify header on eject" in the NetWorker autochanger. This marks any tapes
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corrupted by a SCSI TUR reset/rewind as suspect.
◦ For versions of NetWorker newer than 7.4.1, use Windows Tape Drive Persistence to
ensure that tape device names do not change when Windows is rebooted. This will enable
device paths other than the standard \\.\Tape0 to be used, such as \\.\
Tape2147483646 or \\.\tape4801101. For Windows Tape Drive Persistence, see
http://support.microsoft.com/kb/873337.
◦ Confirm that the Fibre Channel device supports a maximum block size larger than that
being used in NetWorker. This can most easily be done in Windows via the NetWorker
mt command. If the maximum supported block size found via the mt command is too
small (typically 64 or 96 KB), contact the Fibre Channel HBA Vendor for assistance in
modifying the SCSI Scatter/Gather registry setting in the Windows Registry for the Fibre
Channel HBA. The following is an example mt command:
C:\>mt -f \\.\Tape4801110 status
\\.\Tape4801110:
Media Capacity = 292.97GByte
Media Remaining = 289.95GByte
Media Blocksize = 0
Media Partition Count = 1
Media is not write protected
default blocksize = 65536
maximum blocksize = 524288
Linux device configuration: The following guidelines apply to Networker on Linux:
Configure stinit.def to enable variable block size. This requires the st-mt package
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to be installed and /etc/stinit.def to be configured. See the Linux man page for
EMC NetWorker 149