Can I add SSDs to my array if no parity?

[DZMM]

I can't remember what the current status is with SSDs in arrays.  I've just removed my parity drive as I don't need as I have a good cloud backup strategy.  At the moment my cache drive also holds my appdata and I have a couple of unassigned drives for VMs.  I'm wondering if it's possible now that I don't have a parity drive to slow down the SSDs:

 

(i) add an SSD to the array for my appdata i.e. set it to Disk x only and not to use cache?

(ii) add my nVME drive to the array for my VMs?  Would there be any performance hit/gain from the nVME in the array Vs UD?

(iii) I'd add the SSD I'd be able to free up to my cache to go from a single 1TB xfs drive to 2x1TB btrfs drives for 2TB cache capacity.  Would there be a performance hit for my cache?

 

The reason I'd like to do this is just use my cache as a cache and not have any cache only shares, and to also remove the UD plugin - not because it's not good, because it is, but I just like as minimal a setup as possible and it'd be nice to have everything under /mnt/user rather than some stuff under /mnt/disks

 

Thanks in advance for any help

Edited June 28, 2019 by DZMM

[JorgeB]

You can, trim still won't work though.

[DZMM]

8 minutes ago, johnnie.black said:

You can, trim still won't work though.

Thanks - so confirming TRIM only works on the cache and UDs?

 

Is there a big performance difference between a single xfs cache drive or a BTRFS pool?  Or, one that that normal people won't notice?

 

 

[JorgeB]

17 minutes ago, DZMM said:

Is there a big performance difference between a single xfs cache drive or a BTRFS pool? 

I never had performance issues with btrfs pools, and if using raid5/6/10 it's even faster than any single device, but some users have.