I have a ZFS pool in use, what sort of thing would I do with the main XFS array?

[Connor19]

I decided to use ZFS for my main pool consisting of 3 16TB Ironwolf Pro in a raid Z1. I also have a 1TB NVME cache and then the main array is 1 500GB NVME with another one as parity.

 

Being new to unraid I’m just wondering why I need to have those drives in the main array since I’m not using it and just put them there to allow me to get things up and running? Is there something I should be doing with those drives? And also right now I don’t think my cache is doing anything since when writing to my pool I just see the HDDs being written to and not the cache, is this normal or am I missing something?

[ljm42]

The Unraid Array is best when you need flexibility, i.e. the ability to mix and match drive sizes, easily add drives to expand the array, and the ability to spin down individual drives when they aren't in use. The array does not currently support trim, so it is best with spinning hard drives.

 

A ZFS pool is best when you care about speed more than flexibility. Also if you are using SSD/NVMe drives.

 

13 minutes ago, Connor19 said:

And also right now I don’t think my cache is doing anything since when writing to my pool I just see the HDDs being written to and not the cache, is this normal or am I missing something?

 

Make sure the appdata share is set to use the Cache pool, you want Docker data being stored on SSD/NVME drives rather than spinning disks.

 

In terms of writing to cache first and having mover transfer that to the array during the night, currently that functionality works with the array only and not other pools. Because a ZFS pool is already optimized for speed, this functionality is typically not as important for pools as it is for the array.

[Connor19]

I’ll do that, good suggestion, that all makes sense, thanks!

[johntk22]

If your cache drive is faster than other drive, unraid will prefer to write data to the cache first for better performance. But if your cache drive is slow than, unraid will skip it and write data directly to the other drive. 

[JonathanM]

40 minutes ago, johntk22 said:

If your cache drive is faster than other drive, unraid will prefer to write data to the cache first for better performance. But if your cache drive is slow than, unraid will skip it and write data directly to the other drive. 

That is completely wrong. Write destinations are governed by share settings, nothing to do with speed.