Suggestions for planning out VDEVs and ZPools

Thank you again for responding.

This was incorrect. I need to move data off of a 13 year old 2TB HDD and I’m currently using 5.5TB on storage spaces. This means that 8TB of usable space (2x8 in a mirrored vdev) will indeed be too small.

As I can’t really afford 4x8TB at the moment, I’ve decided to go with 3x8TB in a raidz1 with the SSD committed to L2ARC. I might add some small, cheap, mirrored SSD’s to use as SLOG in the future. As I understand it, losing the SLOG vdev isn’t catastrophic for a zpool and I’m willing to sacrifice some SSD’s to the write performance Gods (if they’re cheap enough of course).

I realize that when going with a raidz1 I lose the flexibility of removing vdevs from the pool in the future. However, this seems like the best option given I’m short the cash to buy a 4th drive and I ended up needing more than a single drive worth of storage.

Unfortunately, the only way for me to add NVME storage to the VM (that isn’t a virtual disk on my datastore) is by using the pcie 2.0 1x (~250MB/s) ports on my board. So I might as well stick to SATA.

Without the SLOG, I expect decent write performance but pretty good read performance because of the fairly large amount of L2ARC (for the amount of data I plan on storing).

I plan to just stripe the 3 and 4TB drives in a separate pool with almost no caching (primarycache=metadata and secondarycache=none). This pool would then only be used for unimportant or infrequently accessed data.

I’ve also read this article on the “special” vdev, but considering the quality of SSD’s in my price range, I think it’s best for me to stay far away from this functionality.

Overall, I think I’ll be happy with the all tradeoffs made but only time will tell. Raidz1 might end up biting me in the ass in the future. Thanks again for the help!