- RAID 1: if read data don't match, which drive is at fault?
- Posted by peter on September 24th, 2005
In RAID one with two drives with identical data, if a read results in two
different values, how does the controller (or OS, if software RAID) decide
which one is the faulty drive?
- Posted by Wendel Hamilton on September 25th, 2005
Peter,
If a drive fails then it is marked as faulty in the array thus the raid
controller will not use the faulty disk until the array is rebuilt.
In raid 1 the controller doesn’t actually read both disks and check that the
data is the same it only reads one or the other so the scenario you are
describing should never happen. It always writes to both disks and if can't
write to one of them then the drive is marked as faulty and it’s dropped from
the array and not read again until the array is rebuilt.
If it cant read from one of the disks the it gets the data from the other
and then drops the first drive from the array.
"peter" wrote:
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