Re: unable to mount multi disk volume with recovery mode

[Hugo Mills <hugo@carfax.org.uk>]

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On Sat, Sep 05, 2015 at 12:13:30PM +0200, Ivan Petrovic wrote:
> I don't know... but after btrfs-zero-log now I can't:
> 
> ivan@ipplus-dev:~$ sudo btrfs filesystem df /dev/sdb
> [sudo] password for ivan:
> ERROR: couldn't get space info - Inappropriate ioctl for device
> ERROR: get_df failed Inappropriate ioctl for device
> ivan@ipplus-dev:~$

   You can only use this command while the FS is mounted, and you
can't give it a device, only a mountpoint.

   Also, note that btrfs-zero-log won't help you at all here. It's not
a magic "fix everything for me" tool.

> So you're saying that I can't make first and third partition to work
> with it's data? Maybe I'll try with btrfs-restore, do you think it can
> rescue this 2 drives?

   Unlikely. Like I said, if the FS was using single storage for
everything, a random 33% of the filesystem has gone away. There's
probably not enough of it left to make anything coherent.

   Hugo.

> Thanks
> 
> 2015-09-04 23:17 GMT+02:00 Hugo Mills <hugo@carfax.org.uk>:
> > On Fri, Sep 04, 2015 at 09:07:34PM +0000, Ivan wrote:
> >>
> >> Just to add this:
> >>
> >> ivan@ipplus-dev:~$ sudo btrfs filesystem df /mnt/ambis/
> >> Data, single: total=108.76GiB, used=107.11GiB
> >> System, single: total=32.00MiB, used=20.00KiB
> >> Metadata, single: total=3.00GiB, used=2.34GiB
> >> ivan@ipplus-dev:~$
> >
> >    (If you can't mount the FS, how did you get this output? -- In what
> > I say below, I'm asuming that this was the last output from btrfs fi
> > df on the broken filesystem before it broke).
> >
> >    This is the problem: You're using single for everything. That means
> > that with the loss of one device, approximately one part in three of
> > your filesystem is missing, including the metadata. If the missing
> > drive is truly broken, this filesystem is dead, without any good means
> > of recovery. You'll need to use your backups.
> >
> >    You would have to have RAID-1 system and metadata for the FS to be
> > even partly recoverable with a missing device. (Or RAID-10, -5 or -6).
> >
> >    Hugo.
> >

-- 
Hugo Mills             | Preventing talpidian orogenesis.
hugo@... carfax.org.uk |
http://carfax.org.uk/  |
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