Dot Hill Systems SANnet II 200, Installation, Operation And Service Manual

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1-6 SANnet II 200 SCSI Array Installation, Operation, and Service Manual • June 2005
1.5.2 I/O Expansion Modules
The hot-serviceable I/O expansion modules provide four ports but do not have battery
modules or controllers. I/O expansion modules are used with I/O controller modules in
non-redundant SANnet II 200 SCSI arrays, and in expansion units and SANnet II 200
SCSI JBODs.
1.5.3 Disk Drives
Each disk drive is mounted in its own sled assembly. Each sled assembly has EMI
shielding, an insertion and locking mechanism, and a compression spring for maximum
shock and vibration protection.
Each disk drive is slot-independent, meaning that once a logical drive has been
initialized, the system can be shut down and the drives can be removed and replaced in
any order. In addition, disk drives are field-upgradeable to larger drives without
interruption of service to user applications. The drive firmware is also field-
upgradeable, but the firmware upgrade procedure requires interruption of service.
In the event of a single disk drive failure, with the exception of RAID 0, the system
continues to service all I/O requests. Either mirrored data or parity data is used to
rebuild data from the failed drive to a spare drive, assuming one is assigned. If a spare
is not assigned, you have to manually rebuild the array.
In the unlikely event that multiple drive failures occur within the same logical drive,
data that has not been replicated or backed up might be lost. This is an inherent
limitation of all RAID subsystems and could affect application programs.
An air management sled FRU is available for use when you remove a disk drive and
do not replace it. Insert an air management sled into the empty slot to maintain
optimum airflow through the chassis.
The drives can be ordered in 36-Gbyte, 73-Gbyte, 146-Gbyte, and 300-Gbyte sizes.
Thirty-six-gigabyte drives have a rotation speed of 15,000 RPM, while 73-Gbyte, 146-
Gbyte, and 300-Gbyte drives have a rotation speed of 10,000 RPM.
Caution –
You can mix disk drive capacity in the same chassis, but not spindle speed
(RPMs) on the same SCSI bus. For instance, you can use 36-Gbyte and 73-Gbyte
drives with no performance problems if both are 10K RPM drives. Violating this
configuration guideline leads to poor performance.