HP BL536A, User'S & Service Manual

Page: 19 / 165

Planning the SAS configuration
The key steps in planning the SAS configuration are obtaining a suitable HBA and cable.
The Autoloader uses two SCSI logical unit numbers (LUNs) and requires an HBA with multiple LUN
support. Most HP SAS RAID controllers support Tape Libraries; many non-HP SAS RAID controllers
to not support Tape Libraries. To verify the specifications of your HBA or find a list of compatible
HBAs, review the compatibility matrix on the Enterprise Backup Solutions web site at:
http://
www.hp.com/go/ebs .
CAUTION: Do not connect the Autoloader to a SAS RAID controller unless the EBS matrix shows
that the controller is qualified with the Autoloader. The server might not be able to boot when the
Autoloader 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) 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. To use the other channels, you can purchase a SAS fanout cable with
a connector for each tape drive, as shown in
Example SAS fanout cable (page 19) .
Figure 8 Example SAS fanout cable
The Autoloader has a mini-SAS connector on the 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 supplied 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.
Planning the SAS configuration 19