Hi all!
I’m in the process of migrating my home server from Unraid to TrueNAS with a ZFS pool, as well as upping storage from 2 6TB drives to 4. Unfortunately, because of either my bad luck or incompetence, it seems like one of the drives has died. So, here’s my question. I’ve read up a bit on resilvering and I know that if I replace the dead drive with a larger drive, the pool will be unable to use that extra space until the remaining drives are upgraded, but would there be any other drawbacks? Especially if the pool was left running in this configuration for an extended period.
I definitely see myself upgrading the pool to larger drives in the future, and it would be nice to save myself buying an extra drive that may end up getting replaced before the end of its life. (Note: I’m aware that resilvering isn’t the safest way of upgrading a pool, but the data on the pool is either backed up or non-essential, so I’m fine with the risks)
Not an expert, but as far as I know running with mismatched drives isn’t bad - it’s just a pointless long-term configuration.
Are you planning on mirroring the drives? If you upgrade to 4 drives in the future you could just do 2 mirror vdevs with mismatched drive sizes per vdev. Also I’m surprised you’re bothering with 6TB drives - you can get 14TB very cheap nowadays (recertified).
I looked at doing two vdevs but was put off by the lower usable storage. At a certain point, maybe that’s not as important as I think though.
Yeah, the choice for 6TB wasn’t my best. I got the two older drives a few years back on a Newegg flash sale, and it seemed like plenty, especially considering Unraid’s model of 1 parity drive and 100% usable storage on the data drive(s). Then, when I decided to upgrade, I was too cheap to go buy 4 whole new drives, so I just went with more of what I already had (to add insult to injury, they’re all WD Red drives…).
Yeah lower usable storage sucks, but it’s an okay trade at the moment given its flexibility. raidz expansion is always “right around the corner” but never actually arrives - if it’s merged a raidz array might make more sense for a smaller NAS.
Personally I’ve found that if you’re really budget-conscious or have a low number of disks, MergerFS+SnapRAID backed by BTRFS disks is a better choice for flexibility (very similar to an Unraid setup), since you can add/remove at any time, and they can be mismatched drive sizes.