To add drives should I create new vdev or a new pool

TrueNAS General
1

I am setting up my first NAS for a central repository for several computers and as a local backup and archive. So far, I set up one pool with one vdev (zfs1) consisting of 4 x 2TB drives. I have five 1 TB drives I want to add as zfs2. Should I add them as a second vdev in the existing pool or create a new pool?

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When mixing RAIDZ1 and RAIDZ2 in the same Pool, your are reducing the redundancy to the level of RAIDZ1 for the overall pool. When you lose the Z1 vdev, you will lose everything. It is also suboptimal performance wise.

Make sure non of these drives are SMR and make sure that they are healthy and have a backup ready beacuse I assume these are old drives.

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Thank you for this. Let me make sure I understand: So if 2 drives fail in the z1 pool the data in the z2 pool is lost as well? The drives are old. The 1 TB drives are constellation drives from an old Dell server. They check out good but they have a lot of hours on them.

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If you create a RAIDZ2 VDEV and add it to the same pool as the RAIDZ1 VDEV, then yes, failure of 2 drives in the RAIDZ1 VDEV will kill the entire pool. However, if you create a NEW (second) pool with the RAIDZ2 VDEV, then you will have two independent pools, and failure in the RAIDZ1 VDEV will not impact the data on the other pool.

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Thank you. This is clear. Unless there is some big downside two pools is the answer.

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Data management is biggest downside. You have to decide which pool gets which data, manually. Neither TrueNAS nor ZFS will manage that for you.

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I did not know anything about smr when I decided to build the NAS. I did check if any drives are smr. And the 5 drives for the second pool are. They are Dell Constellation.2 (Seagate). They are 2.5 inch drives. I bought them because they were cheap and I could fit them in my swap enclosure. I figured since they are enterprise drives suitable for RAID that they would work OK. My intent is to use these as archive storage and they will not see that much activity. Am I in trouble?

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You can decide if you want to take the risk with SMR. They give trouble on pool recovery & resilvers. Heavy read & write could be a problem.

SMR vs CMR ServeTheHome

TrueNAS Docs - WD Red SMR Drive Compatibility with ZFS

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Thanks for this. I read both articles. In the long run smr looks like a bad idea so I will probably not use the constellation drives. I do have four 1 TB CMR 3.5 in drives that I think I can squeeze in. I don’t have much data in this pool yet so I can easily delete it and start over.

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Is it certain that those constellation.2 drives are SMR? A googled a bit out of curiosity, but could not find much info.

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I also googled around some and come up with they are not SMR, but CMR (good) drives.
I also found this: The Constellation.2 series is specialized, enterprise-grade storage designed for data centers, not the consumer-grade SMR drives commonly found in budget 2.5-inch external enclosure.

They appear to be (from Seagate spec page) 512Byte drives and are made in both SAS and SATA interfaces..

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Thank you. You are correct. I did a recheck myself via chatGPT of all things and these drives are cmr. I would say most 2.5 inch drives are smr. I am good to go with these. Thanks for notifying me.