Upgrading a drive in a Synology NAS

I’m running out of space. My Synology DiskStation DS1621xs+ (originally provided by Synology, thank you!) is at 89% full. Rather than waiting until it actually runs out, I decided it was time to upgrade one of the drives.

Because I’m running SHR RAID, I can have different sized disks. All my disks in the unit are shucked from Western Digital (WD) or Seagate external enclosures – because it’s cheaper to do that than buy disks outright. This time I’ve bought an 18TB WD drive, which takes about two minutes to remove from it’s case. (Note that before removing, I always test the drive to make sure it’s not DOA. WD and Seagate should still honour the warranty anyway if a drive fails later, and I’ve done this on a shucked WD drive before successfully).

Synology have an article on what to do to replace a disk with a larger one, which is worth reading for other considerations around the process: https://kb.synology.com/en-us/DSM/help/DSM/StorageManager/storage_pool_expand_replace_disk?version=6

This NAS supports hot swapping the disks, so I don’t need to do any prep or power it down – just make sure you have a backup in case it all goes wrong (which you should have anyway if you care about the data).

Here’s a quick video of the drive swapover:

On the Synology itself – Before the upgrade:

10TB drive has been taken out, Synology starts beeping in a concerning way due to being in a degraded state:

New drive inserted:

Using the Action > Repair option to start the rebuild

Then comes the waiting game for the repair, which took about two days to complete:

Note that adding a single 18TB disk is wasting some of the space. If you look at their RAID calculator (which right now goes up to 16TB only but will still show the problem) before taking out the 10TB in bay 6:

Swapping the 10TB to a 16TB only gives 2TB more available space, and 4TB unused, because it hasn’t got available capacity anywhere to mirror all the space the 18TB disk had:

However, if we drop out another 10TB for another 16TB, we see the available space jump up to 60TB and no unsued space. This will be my plan, order another 18TB drive to shuck which should take me all the way up to 62TB available space.

For home use, I really like the Synology Hybrid Raid (SHR) because it provides actual redundancy, as well as easy expansion. I don’t have to commit to buying a bunch of drives at once of all the exact same size, and can gradually increase if and when I need more space. The process of upgrading a disk is so easy too that it’s not an inconvenience when upgrade time comes around.

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