Disk Drives; Backup Batteries; Backup Power Sequence - HP StorageWorks XP12000 - Disk Array Owner's Manual

Disk drives

Each DKU can contain up to 256 hard disk drives. The disk array automatically detects and corrects
disk errors, and an HP support representative can replace any of the disk drives without disrupting
user activity.
The disk array must contain at least one spare disk drive and can contain up to 40. Any of the spare
disk drives can back up any other disk drive of equal rotational speed and equal or lesser capacity,
in any DKU, even if the failed disk and the spare disk are in different array domains.
The XP12000 disk array supports 73 GB, 146 GB, 300 GB and 400 GB Fibre Channel disk drives.
Fibre Channel drives are intended as a high capacity, high performance storage option for high
priority applications such as OLTP, Oracle, SAP, and Exchange.

Backup batteries

In each frame (DKC and DKU), internal nickel-metal-hydride batteries provide backup power for the
cache memory, shared memory, ACPs, CHIPs, and disk drives. If AC input power is lost, the backup
batteries enable the disk array to continue normal operations for up to one minute. If power is not
restored within one minute, the disk array executes either the De-Stage or Backup battery operation
mode.
1. If power is restored during destaging, the disk array continues destaging data and powers off.
2. If power is restored during battery backup, the disk array either automatically restarts or must be restarted
manually, depending on the settting of the AUO PS-ON ENABLE/DISABLE
Figure 3 Backup power sequence
HP representatives will help you determine the best battery mode for your configuration, and will
configure the selected mode during installation.
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