[Users] mount ploop image from read-only fs

Fri Oct 24 06:48:36 PDT 2014

On Fri, 2014-10-24 at 16:35 +0400, Pavel Odintsov wrote:
> Hello!
> 
> Could you send complete ploop_userspace output and dmesg output to
> gist.github.com?

https://gist.github.com/anonymous/343ca13508366d7c5b6a

Roman

> On Fri, Oct 24, 2014 at 4:25 PM, Roman Haefeli <reduzent at gmail.com> wrote:
> > On Mon, 2014-09-15 at 14:49 +0400, Pavel Odintsov wrote:
> >> Hello!
> >>
> >> I found bug! Thx Maxim Patlasov for helping with ploop v1 BAT format.
> >>
> >> Please check version from git and it support ploop v1 and v2 correctly :)
> >
> > It seems, it's not yet working properly for me. I can mount the ploop
> > image, I can mount its filesystem, I can browse the folder structure and
> > everything seems fine, but when I try to read any text file from etc/ or
> > var/log/ I only see garbage or content that certainly belongs to a
> > different file. Something with alignment seems still not correct.
> >
> > Please tell me how I can give you more useful information.
> >
> > Roman
> >
> >
> >
> >
> >> On Sun, Sep 14, 2014 at 2:15 AM, Pavel Odintsov
> >> <pavel.odintsov at gmail.com> wrote:
> >> > Thank you for report, its very useful for investigation. But only one
> >> > difference between v1 and v2 is ploop disk size in header (32 vs 64 bit).
> >> > But I use 64 bit numbers anywhere and everything should work fine. But I
> >> > suppose alignment issues which not handled in my tool.
> >> >
> >> >
> >> > On Friday, September 12, 2014, Roman Haefeli <reduzent at gmail.com> wrote:
> >> >>
> >> >> On Fri, 2014-09-12 at 11:15 +0200, Roman Haefeli wrote:
> >> >> > On Fri, 2014-09-12 at 10:56 +0200, Roman Haefeli wrote:
> >> >> > > Hi Pavel
> >> >> > >
> >> >> > > I might have some more information on the issue. It seems that only
> >> >> > > 'old' ploop images cannot be mounted by ploop_userspace. I actually
> >> >> > > don't quite know the ploop version I used for creating the 'old' ploop
> >> >> > > images,  but I know it works well with images created with ploop v1.6.
> >> >> > >
> >> >> > > Does ploop_userspace know about older image formats?
> >> >> >
> >> >> > No, it's also not the version.
> >> >>
> >> >> Yes, there are different versions... I must have checked on the wrong
> >> >> machine. ploop_userspace works well with images created by ploop v1.11,
> >> >> but not with images created by ploop v1.6.
> >> >>
> >> >> Sorry for the noise.
> >> >>
> >> >> Roman
> >> >>
> >> >>
> >> >>
> >> >> >
> >> >> > > On Thu, 2014-08-28 at 22:53 +0400, Pavel Odintsov wrote:
> >> >> > > > Hello!
> >> >> > > >
> >> >> > > > No, it's not depend on kernel version. I created issue for you and
> >> >> > > > will try to investigate:
> >> >> > > > https://github.com/FastVPSEestiOu/ploop_userspace/issues/10 please
> >> >> > > > track this github issue.
> >> >> > > >
> >> >> > > > On Thu, Aug 28, 2014 at 6:12 PM, Roman Haefeli <reduzent at gmail.com>
> >> >> > > > wrote:
> >> >> > > > > Some more info:
> >> >> > > > >
> >> >> > > > > It works on our test cluster where we have
> >> >> > > > > 2.6.32-openvz-042stab093.4-amd64 installed. The report from below
> >> >> > > > > is
> >> >> > > > > from a host node running 2.6.32-042stab081.3-amd64.
> >> >> > > > >
> >> >> > > > > Is ploop_userspace dependent on kernel version?
> >> >> > > > >
> >> >> > > > > Roman
> >> >> > > > >
> >> >> > > > >
> >> >> > > > > On Thu, 2014-08-28 at 15:59 +0200, Roman Haefeli wrote:
> >> >> > > > >> Hi Pavel
> >> >> > > > >>
> >> >> > > > >> Your tool comes in handy. That is exactly what we'd need.
> >> >> > > > >> However, I had
> >> >> > > > >> troubles using it. I did:
> >> >> > > > >>
> >> >> > > > >> $ ploop_userspace
> >> >> > > > >> /virtual/.snapshot/nightly.0/vz/private/2006/root.hdd/root.hdd
> >> >> > > > >>
> >> >> > > > >>   We process:
> >> >> > > > >> /virtual/.snapshot/nightly.0/vz/private/2006/root.hdd/root.hdd
> >> >> > > > >>   Ploop file size is: 4193255424
> >> >> > > > >>   version: 1 disk type: 2 heads count: 16 cylinder count: 81920
> >> >> > > > >> sector count: 2048 size in tracks: 20480 size in sectors: 41943040 disk in
> >> >> > > > >> use: 1953459801 first block offset: 2048 flags: 0
> >> >> > > > >>   For storing 21474836480 bytes on disk we need 20480 ploop
> >> >> > > > >> blocks
> >> >> > > > >>   We have 1 BAT blocks
> >> >> > > > >>   We have 262128 slots in 1 map
> >> >> > > > >>   Number of non zero blocks in map: 3998
> >> >> > > > >>   Please be careful because this disk used now! If you need
> >> >> > > > >> consistent backup please stop VE
> >> >> > > > >>   !!!ERROR!!! We can't found GPT table on this disk
> >> >> > > > >>   !!!ERROR!!! We can't find ext4 signature
> >> >> > > > >>   Set device /dev/nbd0 as read only
> >> >> > > > >>   Try to found partitions on ploop device
> >> >> > > > >>   First ploop partition was not detected properly, please call
> >> >> > > > >> partx/partprobe manually
> >> >> > > > >>   You could mount ploop filesystem with command: mount -r -o
> >> >> > > > >> noload /dev/nbd0p1 /mnt
> >> >> > > > >>
> >> >> > > > >>
> >> >> > > > >> Despite the errors, I tried to mount the ploop-partition:
> >> >> > > > >>
> >> >> > > > >> $ mount -r  -o noload /dev/nbd0p1 /mnt/
> >> >> > > > >>
> >> >> > > > >> and got:
> >> >> > > > >>
> >> >> > > > >>   mount: special device /dev/nbd0p1 does not exist
> >> >> > > > >>
> >> >> > > > >> Apparently, ploop_userspace wasn't able to read the GPT partition
> >> >> > > > >> table.
> >> >> > > > >>
> >> >> > > > >> Tell me, if you need further information.
> >> >> > > > >>
> >> >> > > > >> Thanks,
> >> >> > > > >> Roman
> >> >> > > > >>
> >> >> > > > >>
> >> >> > > > >>
> >> >> > > > >>
> >> >> > > > >>
> >> >> > > > >>
> >> >> > > > >>
> >> >> > > > >>
> >> >> > > > >> On Tue, 2014-08-19 at 12:48 +0400, Pavel Odintsov wrote:
> >> >> > > > >> > Hello!
> >> >> > > > >> >
> >> >> > > > >> > You can mount ploop from RO root.hdd images with my tool:
> >> >> > > > >> > https://github.com/FastVPSEestiOu/ploop_userspace but it's not
> >> >> > > > >> > stable
> >> >> > > > >> > now. You can try it and provide feedback.
> >> >> > > > >> >
> >> >> > > > >> > On Tue, Aug 19, 2014 at 12:24 PM, Roman Haefeli
> >> >> > > > >> > <reduzent at gmail.com> wrote:
> >> >> > > > >> > > Hi all
> >> >> > > > >> > >
> >> >> > > > >> > > At the university I work, we plan to switch all containers
> >> >> > > > >> > > from simfs to
> >> >> > > > >> > > ploop images on the long run. Despite the many advantages of
> >> >> > > > >> > > using
> >> >> > > > >> > > ploop, there is one major drawback that keeps us from
> >> >> > > > >> > > switching
> >> >> > > > >> > > production already now: We can't mount ploop images from
> >> >> > > > >> > > read-only
> >> >> > > > >> > > snapshots. In case of a recovery of a single file, we have to
> >> >> > > > >> > > copy the
> >> >> > > > >> > > ploop image from the read-only snapshot to some read-write
> >> >> > > > >> > > storage in
> >> >> > > > >> > > order to be able to mount it and extract the file. For CTs
> >> >> > > > >> > > with huge
> >> >> > > > >> > > ploop-images this is a big hurdle.
> >> >> > > > >> > >
> >> >> > > > >> > > Wouldn't it be possible to add a some flag to the 'ploop'
> >> >> > > > >> > > utility to
> >> >> > > > >> > > allow mounting ploop images from read-only storage (by
> >> >> > > > >> > > bypassing some
> >> >> > > > >> > > checks or skipping to set the dirty flag or whatever is
> >> >> > > > >> > > necessary)?
> >> >> > > > >> > >
> >> >> > > > >> > > Cheers,
> >> >> > > > >> > > Roman
> >> >> > > > >> > >
> >> >> > > > >> > >
> >> >> > > > >> > > _______________________________________________
> >> >> > > > >> > > Users mailing list
> >> >> > > > >> > > Users at openvz.org
> >> >> > > > >> > > https://lists.openvz.org/mailman/listinfo/users
> >> >> > > > >> >
> >> >> > > > >> >
> >> >> > > > >> >
> >> >> > > > >>
> >> >> > > > >>
> >> >> > > > >
> >> >> > > > >
> >> >> > > > > _______________________________________________
> >> >> > > > > Users mailing list
> >> >> > > > > Users at openvz.org
> >> >> > > > > https://lists.openvz.org/mailman/listinfo/users
> >> >> > > >
> >> >> > > >
> >> >> > > >
> >> >> > >
> >> >> > >
> >> >> >
> >> >> >
> >> >>
> >> >>
> >> >> _______________________________________________
> >> >> Users mailing list
> >> >> Users at openvz.org
> >> >> https://lists.openvz.org/mailman/listinfo/users
> >> >
> >> >
> >> >
> >> > --
> >> > Sincerely yours, Pavel Odintsov
> >>
> >>
> >>
> >
> >
> > _______________________________________________
> > Users mailing list
> > Users at openvz.org
> > https://lists.openvz.org/mailman/listinfo/users
> 
> 
>