Replacing the Disk Controller Batteries

The disk controllers in storage servers and compute servers have battery-backed write cache to accelerate write performance. If the battery charge capacity degrades, so that the battery cannot protect the cached data for a power loss of 48 hours or more, then the write cache is disabled and the disk controller switches to write-through mode. Write performance is reduced, but no data is lost.

The battery charge capacity degrades over time, and its life expectancy is inversely proportional to the operating temperature. Table 13-1 shows the worst case life expectancy of a battery in Recovery Appliance.

Table 13-1 Battery Life Expectancy

Inlet Ambient Temperature	Battery Lifetime
< 25 degrees Celsius (77 degrees Fahrenheit)	3 years
< 32 degrees Celsius (89.6 digresses Fahrenheit)	2 years