April 11, 20251 yr I have 2 NVME drives in a pool not in Raid 1(dumb, I know). One seemingly stopped working so I rebooted to see one drive was missing. I then attempted the following steps. Thanks for the help. 1. Started/Stopped the array. 2. Made a new cache pool with the one working drive and started the array. 3. Got the Unmountable error. 4. Hard rebooted the server which came back up and found the missing cache drive. I realize it's probably dying, but I've had this happen before last year. SMART passes on this drive even now. 5. Created a pool with BOTH drives back again. 6. Still got the Unmountable error btrfs fi show Label: none uuid: c21ac1df-edb4-4149-8b0f-b992d5d3f776 Total devices 1 FS bytes used 14.32GiB devid 1 size 20.00GiB used 18.52GiB path /dev/loop2 Label: none uuid: 95ca501b-f019-4e4d-8084-84a0a285b8e2 Total devices 1 FS bytes used 412.00KiB devid 1 size 1.00GiB used 126.38MiB path /dev/loop3 warning, device 2 is missing Label: none uuid: 754b3e32-4ddf-4175-9c82-17006b7525a3 Total devices 2 FS bytes used 163.99GiB devid 1 size 1.82TiB used 133.01GiB path /dev/nvme0n1p1 *** Some devices missing Edited April 11, 20251 yr by Riverhawk
April 11, 20251 yr Author I did both just in case you wanted it: fdisk -l /dev/nvme1n1 Disk /dev/nvme1n1: 1.82 TiB, 2000398934016 bytes, 3907029168 sectors Disk model: Samsung SSD 990 PRO 2TB Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes ---- fdisk -l /dev/nvme0n1 Disk /dev/nvme0n1: 1.82 TiB, 2000398934016 bytes, 3907029168 sectors Disk model: Samsung SSD 990 PRO 2TB Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x00000000 Device Boot Start End Sectors Size Id Type /dev/nvme0n1p1 2048 3907029167 3907027120 1.8T 83 Linux
April 11, 20251 yr Community Expert The partition on the other device was wiped, but if nothing else was done, it may still be recoverable, type: sfdisk /dev/nvme1n1 then type 2048 and hit Enter, and post the results, without typing anything else.
April 11, 20251 yr Author sfdisk /dev/nvme1n1 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/nvme1n1: 1.82 TiB, 2000398934016 bytes, 3907029168 sectors Disk model: Samsung SSD 990 PRO 2TB 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 Created a new DOS disklabel with disk identifier 0xaac9aa1b. Created a new partition 1 of type 'Linux' and of size 1.8 TiB. Partition #1 contains a btrfs signature. Do you want to remove the signature? [Y]es/[N]o: I didn't know if I should remove the signature or not. Still at the prompt.
April 11, 20251 yr Community Expert Type N and Enter to keep the signature then type write and Enter, then output from btrfs fi show
April 11, 20251 yr Author Do you want to remove the signature? [Y]es/[N]o: N /dev/nvme1n1p1 : 2048 3907029167 (1.8T) Linux /dev/nvme1n1p2: write New situation: Disklabel type: dos Disk identifier: 0xaac9aa1b Device Boot Start End Sectors Size Id Type /dev/nvme1n1p1 2048 3907029167 3907027120 1.8T 83 Linux The partition table has been altered. Calling ioctl() to re-read partition table. Syncing disks. ----- btrfs fi show Label: none uuid: 754b3e32-4ddf-4175-9c82-17006b7525a3 Total devices 2 FS bytes used 163.99GiB devid 1 size 1.82TiB used 133.01GiB path /dev/nvme0n1p1 devid 2 size 1.82TiB used 133.01GiB path /dev/nvme1n1p1
April 11, 20251 yr Community Expert Solution Now try reimporting the pool with both devices, stop the array, if Docker/VM services are using the cache pool disable them, unassign all cache devices, start array to make Unraid "forget" current cache config, stop array, reassign both cache devices (there can't be an "All existing data on this device will be OVERWRITTEN when array is Started" warning for any cache device), re-enable Docker/VMs if needed, start array.
April 11, 20251 yr Author On the step where I re-add the devices and start the array. Should I change the FS from "auto" to "btrfs" since my cache pool was originally a shared-non-raid pool of 4TB total?
April 11, 20251 yr Author I can't thank you enough. So many questions: 1. Are you an LT employee? I see you saving so many people and you're awesome. 2. Have you ever thought about creating/posting a knowledge base workflow? I see you answering questions like this a lot. Like, how did you know to "do this" then this based on the output? Would it beneficial for you to create something as a guide for people to walk through first? 3. You think my SSD is actually failing or is it a known problem that they sometimes only re-appear after a hard shutdown/reboot? 4. If my drive wasn't recoverable, what would my nightly CA backup provide me if anything? Again, thank you for your time.
April 11, 20251 yr Community Expert I do have many things in the FAQ, but for this type of issue I prefer to do it case by case, since there are many variables. Being wiped was not a device problem, but didn't look at the SMART report, and looks like you removed the diags, CA backup would help with appdata for the containers, I don't think it backs up anything else, but I've never used it.
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