I currently have a storage pool that consists 6 drives in parity. 3x4TB and 3x8TB. I just purchased three more 8TB with the intention of replacing the 3x4TB drives but am having trouble figuring out the best approach. My assumption was I could take one of the 4TB drives out of rotation and replace it with the 8TB as if the 4TB had "failed", then add the 8TB as a replacement, wait for rebalance and then do the same thing 2 more times. Is there a better approach? Also how would I even go about doing this? I assume if I plug the 8TB into the same SATA cord as the original 4TB its not going to magically become part of the pool on its onw so how do I actually handle that in the storage pools UI? Any pointers?
1 Answer
The storage management UI has options to add new drives to the pool and to remove existing ones. Storage Spaces remembers disks by their ID (stored within the disk itself), not by physical connection, so a disk can be moved or temporarily disconnected without damaging the pool.
The safest option is to first add a new disk to the pool, then prepare the old one for removal. Storage Spaces will "evacuate" data from the old disk, and the pool's redundancy requirements will be satisfied at all times. Once the transfer is complete, you will see an option to remove the physical disk entirely. (See official docs.)
(If you don't have enough SATA ports for both disks, you can temporarily connect one disk through a USB-SATA converter. As mentioned before, Storage Spaces won't care. Yes, the transfer will be slower but it's going to be temporary anyway.)
Meanwhile, disconnecting a drive while it still contains data and letting the new one rebuild from parity isn't a great plan; it means risking data loss if another disk happens to actually fail during the rebuild. (That's similar to traditional RAID rebuilds.)
answered Nov 28, 2018 at 7:18
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Interesting, thanks for the details. I don't have any more available SATA connections on my mobo so if I'm reading what your saying correctly though - I could plug in an external USB HD and add that to the pool, then prepare the 4TB for removal which will basically copy its contents to other drives (likely mainly to the new USB drive). Then I can pull the 4TB drive and replace it with one of my new 8TB's and then do the same process on the USB drive (prep it for removal which will basically copy everything back to the new internal 8TB. Then rinse and repeat for the remaining 2x8TB drives?– Andrew.SCommented Nov 28, 2018 at 15:46
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1Well, yes, although you don't have to prepare any the 8TB disks for removal – it should be fine to just move it from USB to SATA. So I would: 1) add new 8TB USB; 2/3/4) remove old 4TB SATA and add 8TB SATA; 5) finally remove the last 4TB SATA and move already-added 8TB from USB to SATA. This will keep the amount of slow USB transfers to a minimum. Commented Nov 28, 2018 at 16:13
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1(What I have in mind is using your new 8TB disk through a USB-SATA adapter/dock/enclosure – instead of a separate temporary USB disk. But if that's all you have, the steps above can still remain the same, except for 5) remove the last 4TB SATA and add the last 8TB SATA, 6) finally remove the temporary USB.) Commented Nov 28, 2018 at 16:22
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I see - that all makes sense. I guess I never expected the ability to move from USB to SATA without it being recognized as a new drive. The three new 8TB disks I have are actual external enclusures (WD Easystores) with the intention to shuck them. So seems like this might work well. Shuck 2 of the 3 and leave one in the enclosure for step 1 and then at the end shuck and replace the last 4TB. Thanks for all your help!– Andrew.SCommented Nov 28, 2018 at 16:27
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This is the first documentation I've found that actually makes sense from the point of view of a user trying to solve a problem! The official docs referenced in the answer are pretty useless except as reminders to someone who already knows how to use the feature. Commented Dec 21, 2018 at 16:05