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Replacing Pool Drive went wrong (Pool Partition Disappeard)

Featured Replies

Hello everyone,

tldr:

former btrfs raid 1 pool cache drives started failing

nvme0 had read errors in the past and i don't trust my backup i could to last night from that drive via Unassigned Devices Copy function into the Array

nvme1 partition disappeard after i could mount it with unassigned devices once and can't be mounted anymore after i started the array.

currently i have no cache pool both nvme are unassigned

  • i am running (acutually it is turned of for the moment while i wait for advise)

    • Unraid 7.1.2

    • 2 btrfs nvme in raid1 in the pool

    • some metal hdd in the array aswell.

    • I use Docker and VM images which are on the cache pool.

  • i noticed occasional errors from nvme0 in the line of with varing sector numbers Kernel: critical medium error, dev nvme0n1, sector 520617864 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2`
    this is going on for a while, i never saw nvme1 cause any error messages.

  • Checking the Smart Attributes i saw that both nvme have around - Power on hours 49,146 (5y, 7m, 8d, 18h) - Data units written 1,584,109,035 [811 TB]
    so i figured it's time for a renewel

  • i read the FAQ about switching a pool drive. i planned to do the following

    • turn of the array

    • power off the box

    • switch drive nvme0 with a new one

    • power on, click the new drive in the position of the missing pool entry, wait for sync to finish

    • do the same with the other drive.

    What really happend:

  • after turning the system back on i tried to put the new nvme into cache1 position and unraid told me that the drive size of the new ssd is to small.

    • the original ones are 2* Corsair mp600 1TB from when it came out oct 2019.

    • the replacements are 2* Corsair mp600 pro xt 1TB

    • Guess the new one falls a few bit short

  • i then wanted to backup the data from the cache, and start with a fresh cache pool from scratch, copy back the files

    • so i switched back to old (failing) nvme0

    • i bootet up

    • when i put the old former drive in the pool position 1 i got the notice in red, that when i start the array all data will be formattet and lost on the cache pool drives.

    • that scared me.

    • i then left the cache drives unassigned and checked if i could access the data of the drive via unassigned plugin which was promising i was able to mount nvme1 and saw that the data was accessable, but i had no disk mounted to copy it

    • i unmounted nvme1

    • i turned of Docker and VM support in the settings.(referring to the FAQ)

    • i started the array

    • i tried top mount nvme1 which wasn't available anymore as an option in the Main overvriew the mount button was grayed out.

    • as a fallback i then mounted nvme0 and used the unassigned Disk Plugin to copy all contents to a backup share in the array. that took a while

    • in the log were many more of the dooming failed to read sector messages. But it seems that all files are copied. but i have no real idea about the integrity. as far as i can see copy ran without errors

Whats next:

  • Should i assume that copy from failing nvme0 worked and read errors were corrected?

  • in the device manager i don't even see the partition on nvme1 anymore are the metadata/partition table affected?

    • put in the new ssd's and copy everything to the new pool and hope for the best?

    • i wanted to backup from nvme1 because i never saw errors from that drive, but i don't get a mount option after the last reboot

      • i am thinking about doing ddrescue image from nvme1 with another computer while i rely on the backuped data i have

i attach one syslog from this morning, showing an attempt to dd if=/dev/nvme1 of=/dev/sdh

  • sdh was a nvme via usb controller i tried to image nvme1 onto. but that faild with read write errors. not sure if it was the controller or nvme1 also failing now.

SMART ATTRIBUTES NVME0
#	Attribute Name	Flag	Value	Worst	Threshold	Type	Updated	Failed	Raw Value
-	Critical warning	0x00
-	Temperature	40 Celsius
-	Available spare	100%
-	Available spare threshold	5%
-	Percentage used	100%
-	Data units read	38,400,185 [19.6 TB]
-	Data units written	1,584,109,035 [811 TB]
-	Host read commands	235,481,675
-	Host write commands	13,878,566,452
-	Controller busy time	27,425
-	Power cycles	45
-	Power on hours	49,146 (5y, 7m, 8d, 18h)
-	Unsafe shutdowns	21
-	Media and data integrity errors	0
-	Error information log entries	70,513
-	Warning comp. temperature time	0
-	Critical comp. temperature time	0
-	SSD endurance remaining	0 %

 SMART ATTRIBUTES NVME1
	Attribute Name	Flag	Value	Worst	Threshold	Type	Updated	Failed	Raw Value
-	Critical warning	0x00
-	Temperature	42 Celsius
-	Available spare	100%
-	Available spare threshold	5%
-	Percentage used	100%
-	Data units read	37,915,086 [19.4 TB]
-	Data units written	1,576,965,705 [807 TB]
-	Host read commands	231,056,110
-	Host write commands	13,980,886,139
-	Controller busy time	28,103
-	Power cycles	45
-	Power on hours	49,145 (5y, 7m, 8d, 17h)
-	Unsafe shutdowns	21
-	Media and data integrity errors	332
-	Error information log entries	12,865
-	Warning comp. temperature time	0
-	Critical comp. temperature time	0
-	SSD endurance remaining	0 %

syslog.txt

Edited by Haube

Solved by JorgeB

  • Author
root@BlackTower:~# btrfs fi show
Couldn't read tree root
Label: none  uuid: 6ed8cfb5-61dd-4db6-9a32-55d4e169ee8c
        Total devices 1 FS bytes used 1.27TiB
        devid    1 size 2.73TiB used 1.44TiB path /dev/sdf1

Label: none  uuid: fe408483-8259-407e-a89e-b3518a13f241
        Total devices 2 FS bytes used 482.56GiB
        devid    1 size 931.51GiB used 791.01GiB path /dev/nvme0n1p1
        *** Some devices missing

Label: none  uuid: 87508b77-65ba-4e84-9b71-2ae2a567ff60
        Total devices 1 FS bytes used 2.24TiB
        devid    1 size 2.73TiB used 2.33TiB path /dev/sdd1

Label: none  uuid: e64e5b29-4c3b-4a93-a188-26bbc8d5b41d
        Total devices 1 FS bytes used 1.87TiB
        devid    1 size 10.91TiB used 1.88TiB path /dev/sdb1

Label: none  uuid: b68bfcc1-11d1-45a1-a153-c462376b088d
        Total devices 1 FS bytes used 2.36TiB
        devid    1 size 2.73TiB used 2.42TiB path /dev/sdg1

Label: none  uuid: 72a72712-4984-40b1-9936-44966d88a39e
        Total devices 1 FS bytes used 144.00KiB
        devid    1 size 2.73TiB used 3.01GiB path /dev/sdc1
root@BlackTower:~# 

2025-05-21 16_37_04-BlackTower_Main.png

blacktower-diagnostics-20250521-1630_after_boot_array_stopped.zip

  • Community Expert

So nvme0n1 does appear to be failing, if nvme1n1 was the other pool device, not clear to me if you managed to backup the pool data or if it's still worth trying to recover the partition from nvm1n1, if it was just wiped, it should be recoverable.

  • Author
13 minutes ago, JorgeB said:

So nvme0n1 does appear to be failing, if nvme1n1 was the other pool device, not clear to me if you managed to backup the pool data or if it's still worth trying to recover the partition from nvm1n1, if it was just wiped, it should be recoverable.

It was around 600 gb, i have a copy from nvme0 but i am unsure about the quality of the backup as there were so many "critical medium error" in the log. I have no idea how to check the integrity of the files.

I would feel better if i get a copy of the data from nvme1 for that reason. I would also like to learn what went wrong, why did the partition disapear i.e.

  • Author

do i need to mount both drives in tandem or would a single drive (nvme1) be mountable by it's own in theoy?

i am thinking about following steps:

  1. remove both nvme and add the 2 new ones create the cache drive pool and copy back the backup data to the cache.

  2. activate docker and vm and see if everything is running

  3. (optional) see if i can salvage data by installing nvme1 in another box and try to rescue the data (if thats possible, never had to deal with btrfs in raid1)

So i want to make sure i am not missing an easy command or unraid quirk to restore the drive (partition) back to working raid1 pool with data for the backup in running array as that would give me the most relyable results right?

  • Community Expert

Type in the CLI:

sfdisk /dev/nvme1n1 then 2048 and hit Enter, then don't do anything else for now, just post the output from that.

  • Author
root@BlackTower:~# sfdisk /dev/nvme1n1

Welcome to sfdisk (util-linux 2.41).
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: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: Force MP600                             
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 (MBR) disklabel with disk identifier 0x5966587d.
Created a new partition 1 of type 'Linux' and of size 931.5 GiB.
/dev/nvme1n1p1 :         2048   1953525167 (931.5G) Linux
/dev/nvme1n1p2: 
  • Community Expert

Hit CTRL+C to abort and repeat, but this time enter 64 instead of 2048, then post output.

  • Author
>>> 64
Created a new DOS (MBR) disklabel with disk identifier 0xf08c845d.
Created a new partition 1 of type 'Linux' and of size 931.5 GiB.
Partition #1 contains a btrfs signature.

Do you want to remove the signature? [Y]es/[N]o: 
  • Community Expert
  • Solution

Type N to keep the signature, then type write to apply the changes, post again output of btrfs fi show

  • Author
root@BlackTower:~# btrfs fi show
Label: none  uuid: 6ed8cfb5-61dd-4db6-9a32-55d4e169ee8c
        Total devices 1 FS bytes used 1.27TiB
        devid    1 size 2.73TiB used 1.44TiB path /dev/sdf1

Label: none  uuid: fe408483-8259-407e-a89e-b3518a13f241
        Total devices 2 FS bytes used 482.56GiB
        devid    1 size 931.51GiB used 791.01GiB path /dev/nvme0n1p1
        devid    2 size 931.51GiB used 791.00GiB path /dev/nvme1n1p1

Label: none  uuid: 87508b77-65ba-4e84-9b71-2ae2a567ff60
        Total devices 1 FS bytes used 2.24TiB
        devid    1 size 2.73TiB used 2.33TiB path /dev/sdd1

Label: none  uuid: e64e5b29-4c3b-4a93-a188-26bbc8d5b41d
        Total devices 1 FS bytes used 1.87TiB
        devid    1 size 10.91TiB used 1.88TiB path /dev/sdb1

Label: none  uuid: b68bfcc1-11d1-45a1-a153-c462376b088d
        Total devices 1 FS bytes used 2.36TiB
        devid    1 size 2.73TiB used 2.42TiB path /dev/sdg1

Label: none  uuid: 72a72712-4984-40b1-9936-44966d88a39e
        Total devices 1 FS bytes used 144.00KiB
        devid    1 size 2.73TiB used 3.01GiB path /dev/sdc1
root@BlackTower:~# 

the previous *** Some devices missing is gone.

also the webui shows now(array is still stopped):

2025-05-21 19_18_25-BlackTower_Main.png

Edited by Haube

  • Community Expert

Now click the first cache slot on the GUI and then remove pool, then back on main, add a new pool with the same name and 2 slots, assign both devices and start the array, see if the pool mounts, any errors post new diags, but if the first device causes errors, it may be better to remove it and use only the other one, assuming it was really a mirror.

  • Author

So new Cache Pool,

  • disks showed up with blue square in the ui.

  • started the array. It mounted!

  • now i use the mover to evac the cache

  • then normal procedure replace hardware and copy stuff back on the then again new cache

no errors so far, but the attachment for good messure

BlackTower_Device.pdf blacktower-diagnostics-20250521-1929.zip

Edited by Haube

  • Community Expert

Looks good so far, and if there are any errors moving the data, try just copying.

  • Author

Thank you very much! i will come back if i struggle again :D

let me send you a crate 🍻

  • Community Expert

Thanks for the beer money!

  • Haube changed the title to Replacing Pool Drive went wrong (Pool Partition Disappeard)

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