Changing your cache settings will not affect your arrays or data, nor is a reinstall of the OS required.  Cached data is simply data written to the cache memory to be written later to the disks, reporting the write as complete - this improves a systems responsiveness and performance.  Turning the cache off (or changing to write-thru) only forces the controller to commit the write to disk before reporting the operation complete and accepting the next write operation. As long as you have a RAID controller with battery-backed cache (PERC 6/i and H700) and no RAID memory problems that have been reported, that cached/unwritten-to-disk data remains safe, as it is kept alive in the cache memory by the battery power, which usually has a 72-hour charge. So, it is not necessary to change it while you resolve your UPS issue, but if you want to, you can change it in either the CTRL-R utility during POST/BIOS or from the OS using OpenManage Server Administrator.
Hi everyone, I have a T310 server with 2 disk onRAID-1, my problem is that I have the cache write policy to Write-back and myUPS has stop responding, so in the meantime I like to change the cache writepolicy to write-through and leave it in that way. My question is, ¿It is possible to changethe cache policy from write-back to write-through without losing any data orwithout reinstalling the os? If it’s possible..¿Can I simple change itfrom the bios on the advanced option without deleting the arrays of disk? ¿it’spossible to change this directly from the OS with any Dell software for Raidcontrollers?. Thanks for the answers and sorry for myenglish. Regards.    
How to change cache policy without loosing data.