Rebuilding cache Pool (add disk back to pool) - making sure got the right steps

[Frostyfruit]

Hi all

 

I took out my unraid server this weekend to give it a clean with high pressure air

 

I connected everything up started the array and docker service was unavailable. 

 

I noticed that my cache disk was not online. So I decided to shutdown the system, re-plugin all the sata / power cables and bring it back up.

 

Long story short, after deleting docker image I was still running into problems with unraid BTRFS warning (device loop2): csum failed root 5 type of problems in my event log.

 

**I've managed to solve this by disconnecting my cache 0 Disk - 500GB SSD**

 

I've now been able to restore my docker images from my templates and everything is running.

 

What i'm unsure of is the best way to join the cache Disk back to the BTRFS pool.

 

i've come across the following thread so hoping for some advice to make sure i dont stuff this up   - **FYI i'm on UNRAID 6.5.3**

 

**The Steps i'm proposing to do are the following, would love some guidance**

0. Take backup of appdata, libvert with CA backup plugin

1. Shutdown array

2. Re-connect cache disk - SSD500GB

3. Restart unraid

4. Un-assign cache disk - SSD500GB

5. Re-assign cache 2 disk to cache slot

6. start aray

7. Check all is working

Stop array

8. Format unnassigned drive

9. assign formatted drive to cache 2 slot

**10. not sure if I will need to do anything else**

 

Thanks for your help!

 

 

Edited October 25, 2020 by Frostyfruit

[JorgeB]

If I understand correctly you currently have cache2 only working? If yes just add cache1 back to the pool, best to wipe it first though.

[Frostyfruit]

Hi Johnnie 

 

Yes cache2 is working

 

to Wipe cache 1 do I need to unassign it, format it and then add it back?

 

that simple?

 

[Frostyfruit]

Hi all love some help here.

 

Based on JorgeB response. I'm trying to work out what would be the best way to wipe Cache SSD disk and then start the array (which i assume the cache pool will re-sync.

 

My initial thoughts to be safe was to just take the SSD out and wipe it on another machine.

 

Is there an easy way to do this within Unraid? with out me getting too complicated?

 

Thanks!

[JorgeB]

to Wipe cache 1 do I need to unassign it, format it and then add it back?

If it's an SSD run blkdiscard:

 

blkdiscard /dev/sdX