RAID5 - Can I replace existing disk with bigger one?

[Tom Lewers]

I have a Proliant server with 3 disks in a hardware RAID5 set. I would like to expand the capacity of the RAID set but there are no spare bays for additional disks. I would like to know what would happen if I replaced one of the disks with a larger one. Would the RAID controller be OK with that and rebuild the set without loss of data and would the additional space on the bigger disk be available for use - either as part of the RAID volume or as a separate volume)?

[Mike Povall · Accepted solution]

If you replace one of the disks with a larger one then you will see no additional space as the new disk will be treated as being the same size as the original. If however you replace all three disks with larger disks, one at a time, and let the array rebuild between each replacement then you will see additional space on completion of the last rebuild.