What's the preferred Btrfs configuration for a cache pool containing four equal-sized SSDs?

 

I did a bit of Googling and it seems that RAID 10 is marginally preferable but that RAID 1 has very similar performance because of the way Btrfs RAID 1 works. The article I found was nearly two years old and a set of test results was even older so it would be interesting to hear from someone who has recent experience. I trust that RAID levels 5 and 6 are still not recommended?

 

Raid10 performs considerably better, especially for writes.

 

Raid 5/6 are still considered experimental, besides, and assuming you'll be using SSDs, you'd lose trim support, so performance would degrade over time.

Thanks Johnnie. RAID 10 it is then. Would that be for both data and metadata, or should the latter remain as RAID 1? I.e.

-dconvert=raid10 -mconvert=raid10

or

-dconvert=raid10 -mconvert=raid1

for the balance command.

End result will be similar, usually use raid1 for metadata.

OK. Thanks.