Adrian Dymorz

Creating a copy of the data and adding the devices to a new pool did work out flawlessly. Not sure about the root cause of the issue. That will probably remain an unsolved mystery.

I currently run "btrfs restore -d /dev/sdb1 /mnt/user/btrfs_restore/" to have a copy of the data before I do anything else. After that I am going to try to add the devices to a new pool. Thanks for your help! Is the link posted on the Unraid Community Rockstars page still valid?

Output of "sfdisk /dev/sdc" and the inputs "64", "N" and "write": Welcome to sfdisk (util-linux 2.38.1). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Checking that no-one is using this disk right now ... OK Disk /dev/sdc: 465.76 GiB, 500107862016 bytes, 976773168 sectors Disk model: WDC WDS500G2B0A Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes sfdisk is going to create a new 'dos' disk label. Use 'label: <name>' before you define a first partition to override the default. Type 'help' to get more information. >>> 64 Created a new DOS disklabel with disk identifier 0xf84ac41d. Created a new partition 1 of type 'Linux' and of size 465.8 GiB. Partition #1 contains a btrfs signature. Do you want to remove the signature? [Y]es/[N]o: N /dev/sdc1 : 64 976773167 (465.8G) Linux /dev/sdc2: write New situation: Disklabel type: dos Disk identifier: 0xf84ac41d Device Boot Start End Sectors Size Id Type /dev/sdc1 64 976773167 976773104 465.8G 83 Linux The partition table has been altered. Calling ioctl() to re-read partition table. Syncing disks. Output of "btrfs fi show": Label: none uuid: ed9ea52f-f8c5-40d9-9814-16f41b39251d Total devices 2 FS bytes used 35.00GiB devid 1 size 1.82TiB used 37.01GiB path /dev/nvme0n1p1 devid 2 size 1.82TiB used 37.01GiB path /dev/nvme1n1p1 Label: none uuid: fb0b5703-1252-43c3-8ee5-d49187894ad9 Total devices 1 FS bytes used 14.90MiB devid 1 size 35.00GiB used 1.52GiB path /dev/loop2 Label: none uuid: c8d7555b-394a-4039-9ea1-ddeaa04a6785 Total devices 1 FS bytes used 440.00KiB devid 1 size 1.00GiB used 126.38MiB path /dev/loop3 Label: none uuid: b7d22b34-fe12-4ec1-aa33-cadfd0a480e4 Total devices 2 FS bytes used 380.41GiB devid 1 size 465.76GiB used 424.00GiB path /dev/sdb1 devid 2 size 465.76GiB used 423.03GiB path /dev/sdc1

>>> 64 Created a new DOS disklabel with disk identifier 0x9a67f18e. Created a new partition 1 of type 'Linux' and of size 465.8 GiB. Partition #1 contains a btrfs signature. Do you want to remove the signature? [Y]es/[N]o:

"sfdisk /dev/sdc" returns Welcome to sfdisk (util-linux 2.38.1). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Checking that no-one is using this disk right now ... OK Disk /dev/sdc: 465.76 GiB, 500107862016 bytes, 976773168 sectors Disk model: WDC WDS500G2B0A Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes sfdisk is going to create a new 'dos' disk label. Use 'label: <name>' before you define a first partition to override the default. Type 'help' to get more information. >>> "2048" as input returned: Created a new DOS disklabel with disk identifier 0xf50eb252. Created a new partition 1 of type 'Linux' and of size 465.8 GiB. /dev/sdc1 : 2048 976773167 (465.8G) Linux Now it is waiting for more input: /dev/sdc2:

"btrfs fi show" returns Label: none uuid: ed9ea52f-f8c5-40d9-9814-16f41b39251d Total devices 2 FS bytes used 35.00GiB devid 1 size 1.82TiB used 37.01GiB path /dev/nvme0n1p1 devid 2 size 1.82TiB used 37.01GiB path /dev/nvme1n1p1 Label: none uuid: fb0b5703-1252-43c3-8ee5-d49187894ad9 Total devices 1 FS bytes used 14.90MiB devid 1 size 35.00GiB used 1.52GiB path /dev/loop2 Label: none uuid: c8d7555b-394a-4039-9ea1-ddeaa04a6785 Total devices 1 FS bytes used 440.00KiB devid 1 size 1.00GiB used 126.38MiB path /dev/loop3 warning, device 2 is missing ERROR: cannot read chunk root Label: none uuid: b7d22b34-fe12-4ec1-aa33-cadfd0a480e4 Total devices 2 FS bytes used 380.41GiB devid 1 size 465.76GiB used 424.00GiB path /dev/sdb1 *** Some devices missing Yes, sdb and sdc were the original pool members.

I did reboot because that is what sometimes helps too.

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?