User's Manual

HP Smart Array 641/642 Controller User Guide E-1

HP CONFIDENTIAL

Writer: John Turner File Name: m-appe hard drive installation & replacement

Codename: darkmatter - antimatter Part Number: 309311-001 Last Saved On: 11/7/02 5:07 PM

Hard Drive Installation and Replacement

Each drive on a SCSI bus must have a unique ID value in the range 0 to 15 (except

ID 7, which is reserved for controller use). This SCSI ID value is set automatically on

hot-pluggable drives in ProLiant servers and storage systems, but values for other

drives must be set manually.

• Do not terminate the drives. The internal cabling in ProLiant servers provides the

required termination of the SCSI bus.

• Do not use drives of different capacity in the same array. The excess capacity of

larger drives cannot be used by the array and is wasted.

• Do not use hot-pluggable drives on the same SCSI bus as non-hot-pluggable

drives.

Drives can be of the Ultra2, Ultra160 (Ultra3), or Ultra320 (Ultra4) type.

General Information About Hard Drive Failure

When a hard drive fails, all logical drives that are in the same array are affected. Each

logical drive in an array may be using a different fault-tolerance method, so each

logical drive can be affected differently.

• RAID 0 configurations cannot tolerate drive failure. If any physical drive in the

array fails, all non-fault-tolerant (RAID 0) logical drives in the same array will

also fail.

• RAID 1+0 configurations can tolerate multiple drive failures as long as no failed

drives are mirrored to one another.

• RAID 5 configurations can tolerate one drive failure.