Installing the cache module – HP ProLiant DL360 G7 Server User Manual
Page 56
Hardware options installation 56
The server supports either of the following:
•
Battery-backed write cache (BBWC) options
BBWC consists of a cache module and a battery pack (also called a BBWC enabler). The DDR cache
module buffers and stores data being written by the controller. When the system power is on, the battery
pack continuously recharges through a trickle-charging process lasting 15 minutes to 2 hours,
depending on the original charge. In the event of system power failure, a fully charged battery pack
can maintain the cached data for up to 72 hours.
•
Flash-backed write cache (FBWC) options
FBWC consists of a cache module and a capacitor pack. The DDR cache module buffers and stores
data being written by the controller. When the system power is on, the capacitor pack charges fully in
about 5 minutes. In the event of a system power failure, a fully charged capacitor pack provides power
for up to 80 seconds. During that interval, the controller transfers the cached data from DDR memory to
flash memory, where the data remains indefinitely or until a controller retrieves the data.
CAUTION:
Do not use this controller with cache modules designed for other controller models,
because the controller can malfunction and you can lose data. Also, do not transfer this cache
module to a different controller module, because you can lose data.
CAUTION:
To prevent a server malfunction or damage to the equipment, do not add or remove
the battery pack while an array capacity expansion, RAID level migration, or stripe size migration
is in progress.
CAUTION:
After the server is powered down, wait 15 seconds and then check the amber LED
before unplugging the cable from the cache module. If the amber LED blinks after 15 seconds, do
not remove the cable from the cache module. The cache module is backing up data, and data is
lost if the cable is detached.
IMPORTANT:
The battery pack might have a low charge when installed. In this case, a POST
error message is displayed when the server is powered up, indicating that the battery pack is
temporarily disabled. No action is necessary on your part. The internal circuitry automatically
recharges the batteries and enables the battery pack. This process might take up to four hours.
During this time, the cache module functions properly, but without the performance advantage of
the battery pack.
NOTE:
The data protection and the time limit also apply if a power outage occurs. When power
is restored to the system, an initialization process writes the preserved data to the hard drives.
Installing the cache module
CAUTION:
In systems that use external data storage, be sure that the server is the first unit to be
powered down and the last to be powered back up. Taking this precaution ensures that the system
does not erroneously mark the drives as failed when the server is powered up.
1.
Power down the server (on page
2.
Extend the server from the rack (on page
3.
Remove the access panel (on page
4.