nik Simpson wrote:
wrote:
On several occasions I have seen situations where faulty UPS's caused
servers wtih RAID 5 arrays to reboot continuosly which caused
corruption to either the RAID array itself or the file system. I am
considering recommending RAID1 whenever possible because I suspect
that it would be more resillient under the same conditions because I
have two seperate copies of the system and I do not suspect that
mirroring would mirror NTFS corruption or suffer from the problems of
RAID 5 array corruption. I would like to hear your opinions on this.

Mirroring would most certainly copy any NTFS level corruption. By the
time it gets to the controller it's just blocks of data. The controller
has no way of knowing that the data has been corrupted in the file
system layer, and will faithfully replicate the corrupt data to both
halves of the mirror.

I am unclear how the logic that mirroring would be any more reliable
than raid5 under conditions of power problems. If the UPS control is
whacked, good ups is cheap insurance. If the goal is to stay with the
lousy ups, possibly feeding a second system with a different power
source and using host based mirroring would help.