Hello there Unraid community.

Unraid 6.2.4

 

I have a SSD Cache currently made of 3 disks

(sdm) 480GB SSD
(sdo) 240 GB SSD
(sdj) 240 GB SSD

I am currently using 22.0GB with 458GB Free.

 

I would like to remove the 480GB SSD to use for something else. Albeit I have been using Unraid for almost a year some of the procedures are still a little difficult to grasp. It's currently using a BTRFS file system. Any help would be much appreciated. I did think about removing the biggest disk and letting it rebuild, however I don't want to put something else in its place, I just want to shrink the cache pool.

 

Thanks in advance.

 

Hi Johnnie

 

Thank you for the quick reply. Just to let you know I tried this and it worked

 

I thought if someone else happened to stumble upon this I might share my experience.

 

So basically the advice above says I need to run this

'btrfs device remove /dev/sdm1 /mnt/cache'

 

To validate which drive to pick you can run the below to show the cache pool file systemB

root@Tower:~# btrfs filesystem show
Label: none  uuid: 41f91f58-0b73-48aa-b3c7-a65acdb13903
        Total devices 3 FS bytes used 20.40GiB
        devid    1 size 447.13GiB used 203.03GiB path /dev/sdm1
        devid    2 size 223.57GiB used 102.00GiB path /dev/sdo1
        devid    3 size 223.57GiB used 100.03GiB path /dev/sdj1

Label: none  uuid: 3fa3efba-3568-4155-b514-198edbd4cb23
        Total devices 1 FS bytes used 1.32GiB
        devid    1 size 10.00GiB used 4.02GiB path /dev/loop0

 

You can then identify the drive and the partition. It probably took me about 30-35 minutes for the drive to become empty after running the command. I opened a second SSH and ran the above command a few times to keep a track of progress. 

 

I've attached a little photo to help explain it too, in the end I ended up adding 2 more drives.