Change cache from raid1 to single drive

[mc_866]

I messed up and rather than starting a new cache pool as I had meant to do with my 2 512 SSD's I incorrectly added them to a pool with my 2TB nvme cache drive.

I stopped the array and removed the drives and the slots. So now I'm down to a single cache drive

 

First it was incorrectly showing 1.5TB capacity so I ran the balance and it didn't change things.
I did some research and found the post below:

So I ran the command below to try and convert back to single vs raid1.

Single: requires 1 device only, it's also the only way of using all space from different size devices, btrfs's way of doing a JBOD spanned volume, no performance gains vs single disk or RAID1

btrfs balance start -dconvert=single -mconvert=raid1 /mnt/cache

I actually ran that twice but am left with 3TB showing above.
Here is a view of the balance status and it appears it's still in Raid1

 

I was of the impression the convert command was supposed to change this.

Also I don't see the drop down next to the balance button shown in the post above.

Any other ideas on how to get this corrected back to a single drive with 2TB of capacity?

Edited December 2, 2022 by mc_866
formatting

[JorgeB]

Having raid1 metadata indicates there's at least one more device that is still part of the pool, please post the diagnostics.

[JorgeB]

You didn't correctly remove the devices from the pool, it still has 3 members:

 

                  Data      Metadata System               
Id Path           single    RAID1    RAID1     Unallocated
-- -------------- --------- -------- --------- -----------
 1 /dev/nvme0n1p1 849.00GiB  3.00GiB  32.00MiB     1.03TiB
 2 /dev/sdb1              -  2.00GiB  32.00MiB   463.73GiB
 3 /dev/sdc1              -  1.00GiB         -   464.76GiB

 

In the end do you wan the current data there to remain in the NVMe device or in the other two?

[mc_866]

I want all the data on the nvme and to revert back to a single cache drive.

 

it only shows a single drive in the gui, is there a way to change it back to a single drive?

[JorgeB]

I want all the data on the nvme and to revert back to a single cache drive.

Assuming you mean the NVMe device and since the data won't fit on just one the the other cache devices you'll need to remove the other 2 members manually, with the array running type in this order:
 

btrfs balance start -f -mconvert=single /mnt/cache

btrfs dev del /dev/sdb1 /dev/sdc1 /mnt/cache

 
When done post new diags

[JorgeB]

16 hours ago, mc_866 said:

Appears only one drive now in the cache.

Yep, you're all set.

[mc_866]

Thanks for the help!!