Remove all drives except for one from Cache pool.

[fodawim]

Is there any way to currently remove all drives except for one from a cache pool without losing the data on the files?

[John_M]

How many drives to you currently have in your cache pool? From the phrasing of the question it seems like it's more than two.

[fodawim]

Right now I have 4, dropping it to one.

 

Currently it is as follows.

 

512GB SSD

256GB SSD

256GB SSD

256GB SSD

 

I'm removing the 256GBs and just leaving the 512.

[JorgeB]

You can, but is kind of a pain, because of how btrfs raid1 works you can only remove one disk at a time, besides that you have to physically disconnect each disk, trying to start array with one unassigned cache disk will result in unmountable cache.

 

If you still want to do it, this is how:

 

1-backup your cache first just in case

2-shutdown server

3-disconnect one of the cache disks

4-Start server, start array, wait for cache to balance, look for cache pool reads/writes to stop, then check the cache page to confirm, when it’s done there can’t be “some devices missing” showing on btrfs filesystem info.

5-go to step 2 and remove another disk

 

Obviously, all data must fit on the single disk you want to use in the end.