RN104, btrfs _merge_bio_hook error, 6.5.0 (RC1) and USB recovery tool

[msq]

Hello,

TL;DR:
Can USB recovery tool be used with Rn104 running 6.5.0 RC1 ..?

Full story:

On my RN104 running 6.5.0 RC1 for last week or so and RAID5 on 4x4TB I got recently btrfs_merge_bio_hook+a4 error. The device remains non accessible on all channels (web, ssh, SMB, rsync).

I found on this forum that one of the moderators recommended using USB recovery tool to try to solve this error.. However - in this particular example in was related to failed upgrade process. And a GA version of OS.

So I would like to try to use this USB tool but with 6.5.0 RC1 or RC2 but was wondering if there are any known limitation of such set up.

And another important question - my understanding is that while using USB recovery tool raid and data basically remains untouched - is this correct assumption?

[kohdee · Accepted solution]

Your problems are not related to beta, so I will close this thread. I will respond in your other thread.

[mdgm-ntgr]

The USB Boot Recovery tool writes the firmware to the internal flash. It doesn't touch the disks. So it is only helpful if there is some corruption on the internal flash which doesn't seem likely in this case, but you can give it a try if you want to.

Btw there is an RC3 now.

[msq]

Hello,

Thank you for your prompt response. I'm just trying to get some data back as it could be easier than download from Glacier....

Ok - I made some progress.

Boot menu >> normal: got obvioulsy btrfs _merge_bio_hook

Boot menu >> Read only: got the same btrfs _merge_bio_hook

Boot menu >> Tech support:
Managed to connect to device. Here is what I found:

# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md0 : active raid1 sdb1[6] sdd1[3] sdc1[4]
      4190208 blocks super 1.2 [6/3] [___UUU]

md1 : active raid6 sdd2[0] sda2[3] sdb2[2] sdc2[1]
      1046528 blocks super 1.2 level 6, 512k chunk, algorithm 2 [4/4] [UUUU]

md127 : active raid5 sdd3[0] sdb3[2] sdc3[1]
      11706506496 blocks super 1.2 level 5, 64k chunk, algorithm 2 [4/3] [UUU_]

unused devices: <none>
# btrfs fi show
Label: '2fe5571e:RaidNas3'  uuid: c763d4aa-2e34-412b-8f91-05b4003019f7
        Total devices 1 FS bytes used 9.09TiB
        devid    1 size 10.90TiB used 9.45TiB path /dev/md127

It  happened that I have output of cat /proc/mdstat when the raid was initially build, so I can easily compare values for my main data array, that is md127:

Tue Apr  5 23:30:01 WEST 2016
Personalities : [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] 
md125 : active raid0 sdg3[0]
      1948664832 blocks super 1.2 64k chunks
      
md126 : active raid1 sdf3[0]
      1948664832 blocks super 1.2 [1/1] [U]
      
md127 : active raid5 sdd3[0] sda3[3] sdb3[2] sdc3[1]
      11706506496 blocks super 1.2 level 5, 64k chunk, algorithm 2 [4/4] [UUUU]
      [===================>.]  resync = 99.9% (3899341892/3902168832) finish=2.0min speed=22753K/sec
      
md0 : active raid1 sdg1[5] sdd1[3] sdc1[4] sdb1[6] sda1[7] sdf1[2]
      4190208 blocks super 1.2 [6/6] [UUUUUU]
      	resync=DELAYED
      
md1 : active raid6 sdd2[0] sda2[3] sdb2[2] sdc2[1]
      1046528 blocks super 1.2 level 6, 512k chunk, algorithm 2 [4/4] [UUUU]
      
unused devices: <none> 

Basically looks like last drive is gone from the array.... Not sure if that is a genuine hardware issue or caused by one attempt to boot device with this one drive removed....

Anyway - when I tried to mount md127 while connected via telnet - this error occurs again on LCD display and telnet stopped responding....

I also tried this, but no luck....

# btrfs restore -v /dev/md127 /dev/null
checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3
checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3
checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E
checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E
bytenr mismatch, want=19070892507136, have=6953034540764995676
Couldn't setup extent tree
checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3
checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3
checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E
checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E
bytenr mismatch, want=19070892507136, have=6953034540764995676
Couldn't setup device tree
Could not open root, trying backup super
checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3
checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3
checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E
checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E
bytenr mismatch, want=19070892507136, have=6953034540764995676
Couldn't setup extent tree
checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3
checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3
checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E
checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E
bytenr mismatch, want=19070892507136, have=6953034540764995676
Couldn't setup device tree
Could not open root, trying backup super
checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3
checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3
checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E
checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E
bytenr mismatch, want=19070892507136, have=6953034540764995676
Couldn't setup extent tree
checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3
checksum verify failed on 19070892507136 found 2D8118ED wanted 8FCE15B3
checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E
checksum verify failed on 19070892507136 found 52289ABA wanted 5594AF4E
bytenr mismatch, want=19070892507136, have=6953034540764995676
Couldn't setup device tree
Could not open root, trying backup super
#

Any further advice will be more than welcome.

[msq]

Post updated and moved here

[kohdee · Accepted solution]

Your problems are not related to beta, so I will close this thread. I will respond in your other thread.