My cache drive is unmountable after rebooting

The filesystem is brtfs running in raid 0

It occurs because one of the drive in the raid 0 array was disconnect and unraid auto start the array without it

and the cache say “Cache Unmountable: No filesystem” I stop the array then connect the disconnected disk and it show up but the cache is still unmountable

You should always post your diagnostics, but basically it the cache remains unmountable with the dropped device reconnect your best bet it to try and recover the data and reformat, this can help with the recovery:

 

https://lime-technology.com/forums/topic/46802-faq-for-unraid-v6/?do=findComment&comment=543490

 

I don’t quite get it what command should I try? if my ssd is on /dev/sda and /dev/sdb should I execute “cd / && mkdir /recovery && mount -o recovery,ro /dev/sda1 /dev/sdb1 /recovery” ?

Command runs only on one of the SSDs, either one if both are readable, try the other if the first one gives an error.

It give out “ERROR: Your Configuration (Raid Level 0) Required 2 drive to mount”

The recovery command work but the file are half the size of the actually file and all file I got seem to be corrupted 

Likely can only get data from one of the devices, superblock was probably destroyed on the other one when it started without it, if that's the case and since it's raid0 it will be incomplete.