HP A7143A RAID160 SA Controller Support Guide, February 2007

Questions and Answers
RAID160 SA Controller Q & A
Appendix E
112
RAID160 SA Controller Q & A
Q:How many RAID160 SA controllers can I install in my system?
A:The maximum number of controllers that you can install in your system depends on your server and
several other factors specific to your configuration. Generally, the maximum number is restricted to the
number of PCI slots not used for other peripherals.
Another limiting factor is the power rating of your system. Each RAID160 SA controller requires 24.9 W. Your
server must be capable of supplying every controller with this amount of power.
Q:How many external drives can I install in my system?
A:Each RAID160 SA controller has four SCSI buses. Each bus can support up to 14 drives.
Q:Does the RAID160 SA controller support SCSI tape drives and CD-ROM drives?
A: No.
Q:What is the data transfer rate for Wide Ultra160 SCSI?
A:Wide Ultra160 SCSI has a data bandwidth of 160 MB per second. Most server applications do not generally
take advantage of the full Ultra160 bandwidth, so performance results will vary from customer to customer.
Q:What is the difference between LVD and Ultra160 SCSI?
A:Low Voltage Differential (LVD) is a signaling level for SCSI protocols. Ultra160 is a SCSI protocol that uses
LVD signaling. Ultra2 also uses LVD signaling, but earlier SCSI protocols used Single-Ended (SE) signaling.
Q:Are Single Ended and Low Voltage Differential SCSI compatible?
A:Yes. When mixing SE drives and LVD drives on a single SCSI channel, all drives switch down to SE SCSI
mode and operate under SE SCSI rules. To maintain a true LVD SCSI bus with its associated performance
advantages, a LVD SCSI channel should only be connected to LVD SCSI drives.
Q:I have several hard drives in my server and in an HP StorageWorks Enclosure 4300. What SCSI IDs do I
assign for these drives?
A:If you are using hot-pluggable drives in a StorageWorks Enclosure 4300, the SCSI IDs are set automatically
according to the bay in which the drives are installed and do not need to be set manually.
The IDs of devices on each SCSI bus do not have to be consecutive. However, the IDs must still be unique to
each device on any given SCSI bus.
Q:Can I use third-party drives (those not manufactured by HP) with the RAID160 SA controller?
A:No.
Q:Why do the drive activity LEDs light up on some drives when my system is idle?
A:The RAID160 SA controller performs several different background activities on the drives when the
controller is otherwise idle. For example, Auto-Reliability Monitoring scans fault-tolerant volumes for defects
and verifies the consistency of parity data, and Drive Parameter Tracking periodically checks the
performance of all drives on the controller (normally on an hourly basis).
Q: What is RAID ADG?
A:RAID ADG is an extension of RAID 5 that allows additional fault tolerance by using two different and
independent parity schemes. Data is striped across a set of hard drives, just as with RAID 5, and the two sets
of parity data are calculated and written across all the drives in the array. RAID ADG provides a high level of
fault tolerance and can sustain two simultaneous drive failures without downtime or data loss. This fault
tolerance level is the perfect solution when data is mission critical.