Notes On Turning Off The Ac Power - RAID Xanadu User Manual

6.4

Notes on Turning Off the AC Power

If you disconnect the AC power without performing the procedures in 6.2 "Power-off Procedure"
or 6.5 "Power Control Means Besides Power Button", the disk array unit saves the cache by
battery.
This unit retains the cache by battery if you turn off the AC power without turning off the power
supply.
The retention time of the battery is limited. Always turn off the AC power after tuning off the
power supply.
If you try to retain the cache past the retention time of the battery, you will lose the data in the
cache.
To recover, data must be restored from backup data saved on magnetic tape or other media.
It takes up to 8 hours from the battery being discharged until it is fully charged.
When it is not fully charged, fast writing that uses the cache (Cache Fast Write) is not done, which
lowers performance.
Since the cache cannot be retained at power-off, data is written to disk without using the cache.
The retention time of a battery that is not fully charged cannot be guaranteed.
Startup when data in the cache has been lost
1. After you turn on the unit, the service LED iterates blinking for 5 seconds and going out
for 7 seconds. The unit does not start normally.
2. Turn off and then turn on the unit.
3. It starts normally.
4. Charging the battery takes up to 8 hours.
Battery backup retention time
Product Name
Xanadu-beta version
Xanadu
The extended BBU varies by Product Name.
Without Extended BBU
24 hours
24 hours
- -
53
With Extended BBU
120 hours (5 days)
72 hours (3 days)