HP Surestore Disk Array 12h - And FC60, Advanced User'S Manual, Page: 46 / 466

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Array Controller Enclosure Components
The BBU contains four LEDs that identify the condition of the battery. Internally, the BBU
consists of two batteries or banks, identified as bank “A” and bank “B.” During normal
operation both of the Full Charge LEDs (Full Charge-A and Full Charge-B) are on and the
two amber Fault LEDs are off. If one or both of the Fault LEDs are on, refer to
"Troubleshooting" on page 359 for information on solving the problem. The Full Charge
LEDs flash while the BBU is charging. It can take up to seven hours to fully charge a new
BBU.
Battery Operation and Replacement
Replace the BBU every two years or whenever it fails to hold a charge, as indicated by the
BBU Fault LEDs. The service label on the BBU provides a line for recording the date on
which the BBU was serviced. Check this label to determine when to replace the BBU.
When a BBU is replaced, it may require up to seven hours to fully charge. The Full Charge
LEDs flash while the BBU is charging, and remain on when the BBU is fully charged.
If you replace the BBU and still experience battery-related problems (such as a loss of
battery power to the controllers or batteries not charging properly), the controller
enclosure may have some other internal component failure. In this case contact your HP
service engineer.
Battery Operation for No Data Loss
The BBU protects the write cache (data which has not been written to disk) for at least 120
hours (five days) in case of a power failure. When power to the disk array is restored, data
in the cache is written to the disks and no data loss occurs. However, if the system is to be
powered off for more than 120 hours, it is imperative that a proper shutdown procedure be
executed or data may be lost. The following are recommendations:
•
Battery status must always be checked and replaced when a failure is indicated.
•
Never remove the BBU without first performing a proper shutdown procedure.
•
For a planned shutdown, make sure that all data has been written to disks before
removing power. This is indicated by the Fast Write Cache LED which will be off when
there is no longer any data in write cache. See
Figure 13 .
•
If the BBU is removed, do not shut off power to the array unless the Fast Write Cache
LED is off. Data in write cache will be posted to disk 10 seconds after the BBU is
removed.