I tried to replace the cache devices by bigger and faster ones. For this I tried to follow to procedure described in the Unraid 6 FAQ. Now I am unable to access the data on the cache drives. What I did trying to replace the drive 1. Add the two new SSDs to the system 2. Stop the array 3. Replace the device in the pool 4. Start the array 5. I then saw the error "Unmountable: Unsupported or no file system" Trying to fix it, I did the following: 1. Stop the array 2. Remove the newly added device from the pool 3. I still got the error "Unmountable: Unsupported or no file system" Now I am trying to restore the data from the cache drive What I see in the UI currently: Overview over devices ("ls -la /dev/sd*"): brw-rw---- 1 root plugdev 8, 0 Feb 27 12:05 /dev/sda brw-rw---- 1 root plugdev 8, 1 Feb 27 12:05 /dev/sda1 brw-rw---- 1 root disk 8, 16 Feb 27 22:36 /dev/sdb brw-rw---- 1 root disk 8, 17 Feb 27 22:46 /dev/sdb1 brw-rw---- 1 root disk 8, 32 Feb 27 22:35 /dev/sdc brw-rw---- 1 root disk 8, 48 Feb 27 12:05 /dev/sdd brw-rw---- 1 root disk 8, 49 Feb 27 12:05 /dev/sdd1 brw-rw---- 1 root disk 8, 64 Feb 27 12:05 /dev/sde brw-rw---- 1 root disk 8, 65 Feb 27 12:05 /dev/sde1 brw-rw---- 1 root disk 8, 80 Feb 27 12:05 /dev/sdf brw-rw---- 1 root disk 8, 81 Feb 27 12:05 /dev/sdf1 Note: There is no /dev/sdc1 Trying to run "btrfs restore -d /dev/sdb1 /mnt/user/btrfs_restore/" shows: warning, device 2 is missing bad tree block 386624946176, bytenr mismatch, want=386624946176, have=0 ERROR: cannot read chunk root Could not open root, trying backup super warning, device 2 is missing bad tree block 386624946176, bytenr mismatch, want=386624946176, have=0 ERROR: cannot read chunk root Could not open root, trying backup super warning, device 2 is missing bad tree block 386624946176, bytenr mismatch, want=386624946176, have=0 ERROR: cannot read chunk root Could not open root, trying backup super Trying to run "btrfs rescue zero-log /dev/sdb1" shows: warning, device 2 is missing ERROR: cannot read chunk root ERROR: could not open ctree Trying to run "btrfs-select-super -s 1 /dev/sdb1" shows: warning, device 2 is missing ERROR: cannot read chunk root ERROR: could not open ctree Trying to run "btrfs-select-super -s 1 /dev/sdb1" shows: Opening filesystem to check... warning, device 2 is missing bad tree block 386624946176, bytenr mismatch, want=386624946176, have=0 ERROR: cannot read chunk root ERROR: cannot open file system Trying to restore partition /dev/sdc1 Hoping to be able to make the missing device accessible again, I tried to use "gdisk" on /dev/sdc, but the output is confusing me: "gdisk /dev/sdc" shows: GPT fdisk (gdisk) version 1.0.9.1 Partition table scan: MBR: not present BSD: not present APM: not present GPT: not present Creating new GPT entries in memory. Command (? for help): q "gdisk /dev/sdb" shows: GPT fdisk (gdisk) version 1.0.9.1 Partition table scan: MBR: MBR only BSD: not present APM: not present GPT: not present *************************************************************** Found invalid GPT and valid MBR; converting MBR to GPT format in memory. THIS OPERATION IS POTENTIALLY DESTRUCTIVE! Exit by typing 'q' if you don't want to convert your MBR partitions to GPT format! *************************************************************** Warning! Secondary partition table overlaps the last partition by 33 blocks! You will need to delete this partition or resize it in another utility. Command (? for help): q Questions What did I do wrong on trying to replace the cache devices? Do you have an idea, how I could be able to restore the data from the cache drives?

Type N and enter to keep the signature, then type write and enter, post new output of btrfs fi show

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Data loss on cache devices - btrfs commands complain "warning, device 2 is missing"

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Solved by JorgeB

February 28, 20242 yr

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April 3, 20242 yr

Community Expert

8 hours ago, PerryS said:

Any idea what might have caused this to happen?

Very difficult to say without seeing the logs from the attempted replacement, but most likely something went wrong there.

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Data loss on cache devices - btrfs commands complain "warning, device 2 is missing"

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