ZFS reconfiguration with hardware upgrade

Software & Operating Systems BSD
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So currently, I have a FreeNas box with 5x4TiB drives in Raid Z2 and a spare SSD that’s on a different (unused) pool. I am wanting to get a disk shelf and have 2x Raid Z2 vdevs of 6 drives each, but I’m not sure if it’s doable. Here’s my though process:

  1. Connect disk shelf with 6 drives to FreeNas host
  2. Create new pool with new disks
  3. Create temp datasets for each current dataset, set compression to the max, and copy everythigng over
    • i.e. foo -> foo_tmp
  4. Take the 5 drives that I’m currently using out of the host box and put them in the shelf with the 1 remaining drive, wiping them in the process
  5. Add the 6 new drives to the in new pool
  6. recreate the original datasets with the correct settings/compression, and copy everything back over
    • foo_tmp -> foo
  7. delete all of the tmp datasets
    • Might go move, delete, move, delete, etc to save space
  8. Add the unused SSD as SLOG

I know this will be tricky, but this is the only way I’ve found to minimize the number of disks needed for the transition and optimize the pool architecture. I think there should be enough room because I’m taking 5x4TiB then moving it to 6x4Tib (with compression) and adding another 6x4TiB when I’m copying over.

Does anybody see any glaring flaws in this plan? Has anybody done anything similar? FWIW I’m still open to the idea of moving everything over to 2 sets of 5x4TiB vdevs with 2 hot spares if it’s easier.

Also, Are there any hardware recommendations? I was looking at the netap DS4246 but I have no idea. The FreeNas host is using consumer parts in a 4U Rosewill case.

Thanks for bearing with this long post and I’ll appreciate any and all feedback!

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The transfer to half a pool, adding a vdev, then manual rebalance with another send/receive is also how I would do it, keeping the redundancy going all the while.

I haven’t got a proper disk shelf (only a rebranded norco ) so I don’t know if it would be loud, or how it presents drives- as jbod single disks, raw or single raid0’s

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I imagine it would depend on the controller/SAS card?

Is that one of the Xyratex ones? Do you like it?

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I got one from a UK reseller, xcaseuk and it’s okay.
A couple of niggles- the lid is a bit odd where it hinges above the drives, and the trays/holders are a bit flimsy, but it fits a lot of them in, and only cost like £350 or probably $200 in real money(I have no idea)

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I don’t even necessarily need a full disk shelf, I just need something to hold more drives lol

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It’s an obsession that can grow in you.
Just stay away from r/homelab and it’s ilk, before you end up with scores of Terrabyte drives, like the other dozens of us.

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