Hey,

I have a btrfs raid1 pool with 3 disks.

root@tower:~$ btrfs fi show /mnt/cache/
Label: none  uuid: a4b126da-bb61-bbb4-471d-034266f28ea1
	Total devices 3 FS bytes used 783.17GiB
	devid    1 size 931.51GiB used 511.03GiB path /dev/sdc1
	devid    2 size 931.51GiB used 510.00GiB path /dev/sdb1
	devid    3 size 1.82TiB used 1021.03GiB path /dev/nvme0n1p1

Is it possible to replace the 2 1TB with a new 2TB?
I tried to read https://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices#Using_btrfs_replace, but I am not sure if it is possible to replace two disks with only one in a single operation.

Also does it confuse the UnRaid GUI or does the WebGUI also support such operations?

 

9 hours ago, Keksgesicht said:

but I am not sure if it is possible to replace two disks with only one in a single operation.

It's not.

9 hours ago, Keksgesicht said:

Also does it confuse the UnRaid GUI or does the WebGUI also support such operations?

You should do it using the GUI, first replace one of the devices with the new one, then remove the other device.

2 minutes ago, Keksgesicht said:

run a btrfs balance on the cache

No need to run a balance, GUI replacement already does that.

 

2 minutes ago, Keksgesicht said:

(this is save??)

Usually yes, but always good to have backups in case something goes wrong.

 

3 minutes ago, Keksgesicht said:

Should I move cache3 in the GUI to cache2 or is it not important.

As you wish, it doesn't make any difference.