Do drive brand/model differences matter in mirrored VDEV sets?

TrueNAS General
1

I’m planning to add mirrors to my striped VDEVs for additional redundancy.

Do I NEED to get the same brand and model of drives that I’m already using, or will it not matter so long as capacity and RPM are similar?

2

As long as you stay away from SMR drives and stick with NAS type models, you should be fine.

3

You’ve listed this as your NAS;

Storage: 16x 4TB drives, 2 VDEVs in RAIDZ3

Adding Mirrors to a RAID-Z3 vDev pool is generally not a good idea.

Of course, if this is a different pool, or different server, then okay.

4

Is there another option for getting a second copy of data without manually pasting to another pool?

5

I think you need to explain exactly what you are asking for. What are you trying to protect your data from?

Are you currently set up with Raid-Z3? Guessing two, 8 wide Raid-Z3 VDEVs in a single pool from your signature info.

6

You are correct about my pool’s layout.

I’d like to prevent the failure of a single VDEV from taking out the entire pool, and only have to perform one operation to transfer data in or out of the pool(s).

I thought having 4 VDEVs in a “striped mirror” or “mirrored stripe” might work.

7

It’s still not clear what you’re trying to do.

If you convert the pool to mirrors only, you’ll need to rebuild the pool from scratch. This would yield half the total pool capacity of what all your drives would have given you as raw capacity.

If you want to add a mirror, see @Arwen’s post.

Are you talking about extra drives that you have or want to purchase? Are you talking about only the existing 16 drives that you are currently using in the pool?

If you’re currently using RAIDZ3, then it means you’ll have to fail 4 drives in the same vdev to lose the entire pool. For striped mirrors, if you fail 2 drives in any of the vdevs, you lose the entire pool.

8

You cannot: By design, losing a vdev necessarily means losing the pool.

I suspect that you want to “mirror” your existing raidz3 with an identical raidz3 vdev: ZFS does not support this. You can however, create another pool, in the same server or preferably in a different, remote, server, and replicate to it as often as you like.

As for matching drives, it is NOT required, and some prefer to mix different vendors to avoid cohort effets and simultaneous mortality.

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