I’d like to swap my spinning disks with SSD drives. I have the new disks and they’re just larger than the old ones. My configuration is a RAID-5 with 3 disks (and one hot spare). Can I hot swap a single disk (HDD to SSD), wait for the new disk to rebuild, then repeat?
I’m thinking that I’d mark down the hot spare, replace it with an SSD, mark the SSD as hot spare, mark HDD 1 as “bad” causing the hot spare to activate, then repeat for the other 2 HDDs. I don’t have a lot of experience with RAID, but did perform a single disk swap once with success.
If this is a bad idea, why? What’s the best way to upgrade?
I’m not sure if this is the right community for this question. If not, please guide me to the right one.
Yes, it’s a bad idea to do it this way. The most likely time a RAID array will fail is during a rebuild as that is a whole bunch of drive activity over a sustained timeframe.
Better to perform a backup or copy, power down, remove all the old drives, install the new ones, power back up, configure a new array (most people recommend to use RAID 6 at a minimum, no hot spare, so you have two drive redundancy) then restore or copy back the data.
This way you can also keep the old drives as a cold backup of sorts, potentially reimporting the configuration if needed.
Consider moving to RAID-6. Single redundancy is not cool anymore.
This is just a homelab, running on old hardware. I don’t think the raid controller supports RAID-6 and I only got 3 new SSDs, and I read that RAID-6 needs 4 drives.
Correct. Get a 4th drive. You will be thankful one day down the road when you are rebuilding the array and you lose a drive during the rebuild.
You might also want to check that your controller really supports hot-swapping. Not all do.
The safest way is to make a backup and restore it to the new array.
Your way sounds pretty fun though. I’m sure the firmware will complain, but once you have a solid backup you can go nuts!
Also consider a solution such as Bachefs - RAID is cool and all, but this will get you most of the way there too. (Decide on the data safety for yourself but I’m running a 90tb pool with 24tb of metadata / cache on SSD)
