Hopefully, this will be a quick one. I have a four drive SSD cache pool in raid 0 btrfs. I want to remove one because it overheats and performs poorly compared to the other three. The pool is only 25% full. Using using Unraid 6.9.2. Not sure if this is a super easy GUI task or if I need to run a btrfs command from terminal first. I read the post from 2020 about this, but I think that was for an older unraid version and the documentation needed to be updated.

 

Is the procedure correct as follows:

1. Disable docker and vm (runs from said pool)

2. stop array

3. Disable disk desired to be removed in gui

4. start array

5. allow balance to complete (moving the data from the removed disk automagically)

6. stop array

7. remove fourth disk slot from pool.

8. start array

9. reenable docker and vm

 

My fear is that the programming may or may not be there to handle the automated removal for the raid 0 situation. If not, then my procedure would lead to data loss/corruption. I have a backup of all data on cache so I'm not worried about that.

Edited November 10, 20214 yr by wildfire305
marked as resolved

For raid0 you can't use the GUI, you can do it manually, if interested I can post the instructions.

11 minutes ago, JorgeB said:

For raid0 you can't use the GUI, you can do it manually, if interested I can post the instructions.

I would greatly appreciate it. I'm a noob, but not scared of the command line, I just grew up on the other side of the tracks with commodore and dos.

I had played with the btrfs command line tools with some spare disks in a usb enclosure a little while ago, but I don't remember much. I really like that filesystem.

Edited November 9, 20214 yr by wildfire305

With the array started type:

 

btrfs dev del /dev/sdX1 /mnt/cache

 

Replace X with the correct letter and adjust mountpoint if needed, i.e., using a different named pool.

 

When that's done, you'll get the cursor back, you need to reset the pool assignments, to do that:

 

Stop the array, if Docker/VM services are using the cache pool disable them, unassign all pool devices, start array to make Unraid "forget" current cache config, stop array, reassign remaining devices (there can't be an "All existing data on this device will be OVERWRITTEN when array is Started" warning for any cache device), re-enable Docker/VMs if needed, start array.

 

 

 

 

Thanks! Those instructions worked perfect. The older ssd had drug it down to 125 MB/s. Now its over 500 MB/s with the offending disk gone.