I have 2x8tb and 2x10tb drives. I had been planing on just mirroring the drives and putting them in a pool for 18tb's of space, but cannot figure out how to configure them to do so. Does Unraid not allow for mirroring like this?

 

Thanks for the help.

Unraid is not RAID. If you have a single parity disk and a single data disk, then that configuration is effectively a mirror simply due to how parity works. But in the general case, parity does not contain any data. It just contains parity bits that allow the data for a missing data disk to be calculated from all the other data disks.

 

It is possible to have btrfs raid1 mirror in the cache pool.

 

But it would be better if you learned more about how Unraid actually works instead of thinking in terms of mirrors. Here is an Overview from the wiki:

 

https://wiki.unraid.net/UnRAID_6/Overview

 

There is also some pretty good introductory material on the website:

 

https://unraid.net/product

So if I have an array consisting of one 10tb parity drive and then the rest of the drives (1x10tb and 2x8tb) that is a valid setup with redundancy?

17 minutes ago, Mushroom said:

So if I have an array consisting of one 10tb parity drive and then the rest of the drives (1x10tb and 2x8tb) that is a valid setup with redundancy?

You would be able to reconstitute data from one drive failure in that setup. Dual parity would protect you from 2 simultaneous drive failures. 

If I set up a second parity drive I am guessing that it would also need to be 10tb? Also, with this setup how much more storage am I able to add?

Yes.  If you set it as you described, you will have an array with a data capacity of 26TB with single parity.  @SpencerJ has described the parity options and the protection that each parity setup option provides.   (Personally, I would wait until I had eight data drives before I would consider going to dual parity.  But I monitor my servers carefully, run monthly parity checks, and address any problems as they arise.) 

 

You can add data drives until you each the limit of 28 data drives.  

Edited July 24, 20196 yr by Frank1940
26TB was 26GB

2 minutes ago, Mushroom said:

If I set up a second parity drive I am guessing that it would also need to be 10tb? Also, with this setup how much more storage am I able to add?

Correct. Parity drives need to be as big as your largest data drive. Storage thereafter is as much as your hardware can accommodate up to 28 data drives iirc.

Thanks for all the help.