Unit Emergency Power Off Switch; Service Processor (Svp); Disk Array Frames; Disk Drives - HP StorageWorks XP20000/XP24000 - Disk Array Owner's Manual

Unit emergency power off switch

The UNIT EMERGENCY POWER OFF switch is located on the back of the DKC cabinet. For more
information about this switch, see

Service Processor (SVP)

The Service Processor inside the controller performs these functions:
Collects performance data on the system for diagnostic testing and analysis
Provides your HP support representative with maintenance access to the system
Hosts system management software
Your HP support representative uses the SVP to configure, maintain, and upgrade the system software
and hardware. The SVP is not a customer-accessible component.
To protect your security, the SVP does not have access to any user data stored on array disks.
If you have extreme availability requirements, an optional second SVP is available.

Disk array frames

DKUs are optional cabinets that allow you to expand the disk array's storage capacity. DKUs contain
physical disk drives. The disk array can include up to four DKUs. Four DKUs fully populated with disk
drives (plus the disk drives in the DKC) provide up to 1152 total hard disk drives for the XP24000
and 240 total hard disk drives for the XP20000.

Disk drives

The DKC can hold up to 128 hard disk drives for the XP2400 and 120 hard disk drives for the
XP20000. Each DKU can contain up to 256 hard disk drives installed on the XP24000 and 240 hard
disk drives installed on the XP20000. There can be from zero to four DKU's. The disk array
automatically detects and corrects disk errors, and an HP support representative can replace or add
disk drives without disrupting user activity.
The disk array can contain up to 40 spare disk drives for the XP24000 and 16 spare disk drives on
the XP20000. 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 XP24000/XP20000 disk arrays support several sizes of Fibre Channel, SATA, and solid state
disk drives. Fibre Channel drives are intended as a high-capacity, high-performance storage option
for high-priority applications.
As shown in
DKU frames. Each box holds four groups of 16 drives for the XP24000 and holds four groups of 15
drives for the XP20000. The drives in the HDU connect to the DKA through a Fibre Switch (FSW) and
the FC-AL path. The lower drives in an HDU (FSW-L) connect to the DKA pair in Cluster 1, and the
upper drives in an HDU connect to the DKA pair in Cluster 2.
"Emergency power
Figure 6, disk drives install in the Hard Drive Unit (HDU) boxes mounted in the DKC and
off" on page 41.
XP24000/XP20000 Disk Array Owner's Guide 25