Attempting to upgrade cache pool SSD -- stuck on unmounting

[kaiguy]

Hello! I recently wanted to upgrade one of my 4 SSD cache pool drives with a larger one. I shut down the array, removed the old drive, replaced it with the new, and restarted my server. I forgot to enter maintenance mode, however, so unRAID went ahead and mounted the array. When I tried to shut down the array to replace the drive in the webgui, it's just sitting there trying to unmount.

 

The syslog is reporting:

 

Jun  8 16:54:51 titan emhttp: shcmd (3277): umount /mnt/cache |& logger
Jun  8 16:54:51 titan root: umount: /mnt/cache: target is busy
Jun  8 16:54:51 titan root:         (In some cases useful info about processes that
Jun  8 16:54:51 titan root:          use the device is found by lsof(8) or fuser(1).)
Jun  8 16:54:51 titan emhttp: Retry unmounting disk share(s)...
Jun  8 16:54:53 titan kernel: BTRFS info (device sdd1): found 10 extents
Jun  8 16:54:53 titan kernel: BTRFS info (device sdd1): relocating block group 1859598286848 flags 17

I really hope I didn't muck things up. Any suggestions on what I can do to get the array stopped and this drive replaced? THANKS!

[kaiguy]

So over the past hour unRAID is still trying to unmount, but /mnt/cache is keeping it from doing so. 2 of my remaining 3 SSDs in the cache pool are showing consistent activity, so I have no idea if it's just reading and trying to unmount, or if there's some sort of rebalancing going on (or whatever... I'm not all that familiar with BTFRS). I'm not going to try to powerdown the server until someone can chime in on a good option for how to deal with this... ugh.

 

Edit: Ok, shortly after this post, the webgui returned. Not sure how BTFRS works, but when it was finally able to unmount, I assigned the new drive and now it's rebalancing. Data appears to be safe. Strange how it took so long to be able to do this, but I'm glad all is well. Just posting this in case someone else runs into a similar experience.

Edited June 9, 2017 by kaiguy

[JorgeB]

It was doing a balance, you need to wait for it to finish before you can unmount the array, check the FAQ, lots of info on how to add/remove and replace cache devices.