HP StoreEver MSL2024, MSL4048, MSL8048, and MSL8096 Tape Libraries User and Service Guide (AK378-96059, December 2012)

HBAs, review the compatibility matrix on the Enterprise Backup Solutions website at: http://
www.hp.com/go/ebs.
CAUTION: Do not connect the library to a SAS RAID controller unless the EBS matrix shows that
the controller is qualified with the library. The server might not be able to boot when the library is
connected to a non-supported SAS RAID controller.
About SAS
Serial Attached SCSI (SAS) is a computer bus technology mainly used to transfer data to and from
storage devices, including disk drives and tape drives. SAS-1 (LTO-4) is designed to transfer data
at 3 Gb/sec, which is comparable to the speed attained by Ultra320 SCSI. SAS-2 (LTO-5 and
LTO-6) is designed to transfer data at 6 Gb/sec.
SAS cables and connectors
SAS uses serial connections, with a direct connection between the host server and each of the
storage devices. This eliminates the need to configure SCSI busses and assign SCSI IDs, as is
required for parallel SCSI devices.
Most SAS HBA ports have four SAS channels. A tape drive uses one channel, so each HBA port
can support up to four tape drives. You can use a cable with one connector on each end, but only
one channel will be used. The HP SAS fanout cable recommended for use with the library can
connect up to four SAS tape drives to a single SAS HBA port. See “Example SAS fanout cable”
(page 41).
Figure 35 Example SAS fanout cable
The library has a mini-SAS connector on each tape drive. The connector is keyed in location 4,
which is the standard location for end devices. If you use a cable other than the one recommended
for use with the product, verify that it is keyed in location 4.
CAUTION: Mini-SAS connectors are keyed. Do not force a SAS cable's mini-SAS connector into
the tape drive mini-SAS connector because it might be keyed differently.
SAS signal rates require clean connections and a minimum number of connections between the
HBA and the device. Do not use adapters or converters between the HBA and the device. HP
recommends a maximum SAS cable length of six meters.
CAUTION: High quality SAS cables rated at the transfer rate of the SAS components are required.
Always verify that the SAS cable you are using is rated for the data transfer speed of the interface
of your components. SAS cables described as "equalized" may not support 6 Gb/s data rates
and should not be used with LTO-5 tape drives unless these cables are verified for 6 Gb/s data
rates. For optimum performance, only use HP cables of the length specified as qualified for your
products.
Planning the SAS configuration 41