Altering SSD Cache setup

[fluisterben]

So, I currently have 5 SSDs in a Cache btrfs raid10 array, superfast, very happy with it.

But I need to remove a controller card, which powers 3 of the 5 SSDs currently.

Those 3 powered by this controller are M.2 NVMe, and only one of those M.2s can remain by putting it in a slot on the mainboard. So I'll at least try and move that one.

This leaves me with 2 of 5 cache drives suddenly missing.

What is the best procedure here for this?

(Besides of course making sure I copy the data from the cache array so that I have a backup.)

Should I first convert the cache array to, say, raid 0, as to not lose anything when removing drives?

 

And yes, I'll be adding 2 (new) SSDs, so I can recreate the cache with 5 media again. Not sure about the order of doing all this though.

Anyone with experience doing this?

 

[JorgeB]

On 10/2/2019 at 7:17 AM, fluisterben said:

Should I first convert the cache array to, say, raid 0, as to not lose anything when removing drives?

Only raid6 can still work with 2 missing devices, and we'd need to use raid6 for metadata also, which is not recommended, though it should be OK for a little while, just make sure everything is backed up.