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midna

Member

Registered: 2017-05-14

Posts: 4

[Btrfs] data recovery: partition is unmountable

Hello everyone.

I have "little" problem with my backup partition...
Drive with broken filesystem is in LUKS container (without LVM).

sdd                      8:48   0   2.7T  0 disk  
└─sdd1                   8:49   0   2.7T  0 part  
  └─TOSHIBA-3TB        254:4    0   2.7T  0 crypt

I cant mount that filesystem even with "-t btrfs -o recovery". (mount complains about bad superblock/filesystem)
When the failure occurred I had few warnings (in dmesg, btw that filesystem remounted as read-only) about bad leaf etc. "btrfs check --repair" repaired that filesystem and it was working as expected.
But one day i had something like freeze of my pc, just everything stopped, drives were spinning but OS just stopped working (linux-lts kernel), it was in that state for about 10 minutes leaved in hope that it will eventually start working (it wasn't even visible on network, so it's not xorg fault), but it didn't, after reboot my filesystem was unmountable.
I was searching on wiki for solutions and after trying "btrfs check --repair /dev/mapper/TOSHIBA-3TB", it did nothing. so I did:

btrfs check --repair --init-extent-tree /dev/mapper/TOSHIBA-3TB

And here is the output:

enabling repair mode
Checking filesystem on /dev/mapper/TOSHIBA-3TB
UUID: ddb08d53-67a8-42b4-87f6-309ea88b2586
Creating a new extent tree
Failed to find [29605888, 168, 16384]
btrfs unable to find ref byte nr 29622272 parent 0 root 1  owner 1 offset 0
Failed to find [29605888, 168, 16384]
btrfs unable to find ref byte nr 29638656 parent 0 root 1  owner 0 offset 1
parent transid verify failed on 29655040 wanted 2792758 found 2792759
Ignoring transid failure
checking extents

This command is running now for about 2 weeks. I don't know if I should ctrl+c that and try btrfs-zero-log or other tool.

Last edited by midna (2018-09-02 20:43:13)

graysky

Wiki Maintainer

From: :wq

Registered: 2008-12-01

Posts: 10,734

Website

Re: [Btrfs] data recovery: partition is unmountable

Something similar happened to me a few years ago.  I do not use btrfs any more.

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Ropid

Member

Registered: 2015-03-09

Posts: 1,069

Re: [Btrfs] data recovery: partition is unmountable

The stuff is either not well documented, or I just overlooked something. There should be a mailing list somewhere that the people who wrote the actual code read, and if you find it and post there, someone might know about something you can do.

Something similar happened to me a few years ago.  I do not use btrfs any more.

The problem is if you get addicted to the features it has. I want those hourly snapshots to browse through. They saved me a few times when I was an idiot and wiped stuff by mistake. Those hourly snapshots can be transmitted to another location as some sort of incremental backup and it just takes a few seconds. This is just too good.

Last edited by Ropid (2017-05-14 13:19:50)

midna

Member

Registered: 2017-05-14

Posts: 4

Re: [Btrfs] data recovery: partition is unmountable

Something similar happened to me a few years ago.  I do not use btrfs any more.

I've seen that topic from google results, when I was doing research.

I don't know if that is similar to me, my problem occurred after system freeze which can be any bug in my hardware/kernel/any driver.
Also, btrfs got way better since your problem, I'm using it as filesystem for root and home on my laptop since a year now and I have no problems at all.

The stuff is either not well documented, or I just overlooked something. There should be a mailing list somewhere that the people who wrote the actual code read, and if you find it and post there, someone might know about something you can do.

Yes it lacks some form of proper documentation, and mailing lists just for now have some raports of "bricked" filesystems, but solution in most cases is just mounting with -o recovery or doing some magic with "btrfs check --repair".

I will try to contact people on their IRC. I'll report back solution if there will be any...

Last edited by midna (2017-05-14 18:35:41)