Cody wrote:
Hi Everyone,
I have an 8-disk raid5 array (each is 500GB SATA). The first disk
sda1 shows bad sectors (from smartd). mdadm reports that the array
is fine, but I want to replace or re-add the drive. Should I replace
it? It's the oldest drive in the array (the disk is ~3 years old).
If you have full backups of the array and can tolerate the unplanned
complete failure of the drive, then you could leave it in service.
With an array of this size and age, you should be running:
echo repair > /sys/block/mdX/md/sync_action
on a regular basis to ensure the whole array is being written to and
helping to minimise the chance of you hitting a bad sector on another
drive during the resync after having replaced the faulty drive.
Also, can I replace it with a 1TB disk and add it as two partitions
(assuming that 2 partitions of the correct size can be created)? I
have read of RAID schemes that involves partitioning each disk into
smaller increments, but this seems inherently unsafe to me unless
mdadm understands that two partitions are on the same device and
organizes parity accordingly.
If by this you mean that you wish to replace your faulty drive with one
500GB partition and grow the array to be able to add the second 500GB
partition, then no, this is a bad idea on two counts:
When this drive fails in the future, you lose two components and the
array is unrecoverable (RAID 5 only allowing single component redundency).
Having two components on the same physical device would impact
performance due to the head having to constantly re-seek between the two
partitions.
Regards,
Richard
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