Hi, I've one existing Unraid server with both Array (on spindle disk), and NVME pool, after running months on it, I realised how infrequent I am using the array as my NVME pool are large eough to withhold majority of my work.

I'm thinking of downsizing my current unraid box to be just a small and powerful server running multiple test VM on its NVME pool, so its a relatively smaller and nicer case that I can have reason to work on :-)

Now, only 2nd Unraid server, it''ll be very defined usage

• Cold or not as-hot storage requirement, capacity is important so it can hold my first Unraid nvme-only backup or some older archive

• 6x16TB mechanical drive (fully populated), and potentially 2 x 2.5'' SSD for cache

• It runs on my very old but trusty SuperMicro C236 mobo with Intel E3-1260L v5 with 32GB ECC memory

My thoughts:

• Since this is only a box not running my VM, and will store my back and archive, I'm thinking of running this without array, just run the 6x16TB as a pool of ZFS (perhaps a RaidZ2) which still serve my requirement well enough from capacity standpoint

• I noted the benefit of ZFS pool as it have better performance (combined I/O of the drives), give same level of redundancy (RaidZ2 vs dual parity); but likely at an expense of compute and memory usage?

• I've 10Gbps network so running ZFS likely will give me better throughput while copy/backup large amount of files.

• I do not need a mixture of drive size (which is a pros with the Array)

My questions:

• would my cpu/memory fit for purpose for the ZFS pool?

• Is there any other gotcha of ZFS vs Array that I need to know?

Would appreciate all the advises based on my use-case. Many thanks

3 hours ago, uniqf said:

would my cpu/memory fit for purpose for the ZFS pool?

Should be fine, ZFS can use more RAM if available but doesn't require it. It would work fine with 8GB.

Just keep in mind that future expansions are more limited with ZFS, though you can still expand the pool using the CLI from Unraid 7.2, disk will need to be the same size or larger, but you cannot use the extra capacity.

Also note that if you lose the pool, you lose all the data, unlike the array, where each disk is an independent filesystem, so make sure you have adequate backups.

thanks @JorgeB , it makes sense. May be like most users i wouldn't have any other backup rather than hoping the Raidz2 with dual drive failure as the safety net. This statement got me thinking about the Array where individual drive data are still intact if catastrophic things happened.

many thanks....while I think dual drives failure is not common or likely its very marginal risk, not sure if I'm ready for it if it happens.

Will give it a hard think about it.