HP StorageWorks X9720 Network Storage System Controller User Guide (496784-002, December 2009)

DescriptionItemDescriptionItem
Mini-SAS universal connector 46Battery 11
Controller Status LED7Battery 22
Mini-SAS universal connector 38Mini-SAS universal connector 53
Mini-SAS universal connector 19Mini-SAS universal connector 64
Mini-SAS universal connector 25
Battery
The battery provides uninterrupted power backup to the cache module in the event of a power failure
for at least 96 hours. The Nickel Metal Hydride (NiMH) batteries in the module are continuously
recharged when the system power is on.
Disposing of old batteries
WARNING!
The controller contains Nickel Metal Hydride (NiMH) batteries. There is risk of explosion, fire, and
personal injury if the battery pack is incorrectly replaced or mistreated. To reduce the risk of personal
injury:
• Do not attempt to recharge the battery.
•
Do not expose to temperatures higher than 60
o
C.
• Do not disassemble, crush, puncture, short external contacts, or dispose of in fire or water.
• Replace only with HP spare designated for this product.
For more information about battery replacement or proper disposal, contact your HP Authorized
Reseller or your Authorized Service Provider.
CAUTION:
Do not dispose of batteries, battery packs, and accumulators with general household waste. Use the
public collection system or return them to HP, your authorized HP Partners, or their agents. For more
information about proper disposal, contact an HP Authorized Reseller or Service Provider.
Cache module
To enable faster data access from disk storage, the cache module performs two types of caching:
• Posted-write caching—the controller writes user data in the cache memory on the module rather
than directly to the drives. Later, when the storage system is idle, the controller writes the data to
the drive array.
• Read-ahead caching—the controller detects sequential array access, reads ahead into the next
sequence of data, and stores the data in the read-ahead cache. Then, if the next read access is
for the cached data, the controller immediately loads the data into system memory, avoiding the
latency of a disk access.
X9720 Network Storage System Controller User Guide 11