[linux-lvm] Missing link in /dev/<domain>?

[linux-lvm] Missing link in /dev/<domain>?

[Greg Freemyer]

All,

Re: SuSE 10.1 w/ 2.6.16 enhanced kernel from the distro.

I had a non-graceful shutdown of a fileserver last night.

Today, the /dev/mapper directory seems to have an extra entry:

my-domain-config
my-domain-home
my-domain-data
my-domain-data-real
control

The unexpected entry is the -data-real one.

The -data entry seems to be corrupted because if I try to mount that I
get "no superblock".  OTOH -data-real can be mounted and has my data
in it.

Another issue is in /dev/<my-domain> I only have 2 links (config and home).

If I manually create the missing data link and point it to -data-real
I can mount my data filesystem, but after a reboot the link is missing
once again.

I'm running SuSE 10.1 which has a dynamically created /dev directory,
so I have no idea where to look to get the missing link to be
recreated properly

So, I guess my first question is what's going on with -data vs
-data-real?  And should fixing that cause the dynamic /dev to properly
start recreating my full set of links?

Greg
-- 
Greg Freemyer
The Norcross Group
Forensics for the 21st Century

Re: [linux-lvm] Missing link in /dev/<domain>?

[Alasdair G Kergon]

On Fri, Aug 11, 2006 at 01:59:35PM -0400, Greg Freemyer wrote:
> my-domain-data
> my-domain-data-real

> The unexpected entry is the -data-real one.
 
Did you try anything with snapshots?

See what vgmknodes does.

Post the output of dmsetup info -c and lvs -va.

Alasdair
-- 
agk@redhat.com

Re: [linux-lvm] Missing link in /dev/<domain>?

[Greg Freemyer]

On 8/11/06, Alasdair G Kergon <agk@redhat.com> wrote:
> On Fri, Aug 11, 2006 at 01:59:35PM -0400, Greg Freemyer wrote:
> > my-domain-data
> > my-domain-data-real
>
> > The unexpected entry is the -data-real one.
>
> Did you try anything with snapshots?
>
Yes, I routinely perform a snapshot everynight via cron.  No idea if a
snapshot existed when the machine went down.

> See what vgmknodes does.
>
I renamed the manually created link from data to data.tmp, then ran vgmknodes.

The data link was successfully recreated.

> Post the output of dmsetup info -c and lvs -va.
>
# dmsetup info -c
Name             Maj Min Stat Open Targ Event  UUID
TruStore--Data-data-real 253   2 L--w    1    1      0
LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBxxpvaosSsuQnSubLnpkprJIBEdn1VHiV-real
TruStore--Data-home 253   0 L--w    1    1      0
LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBHU7HFSYOTsxTwH6Pg1c4k0UQOK7O4j6X
TruStore--Data-data 253   3 ---w    0    0      0
LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBxxpvaosSsuQnSubLnpkprJIBEdn1VHiV
TruStore--Data-config 253   1 L--w    1    1      0
LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBG5XBMCNoneiIFa16MFUHMmmhPgvEF3da

# lvs -va
File descriptor 4 left open
    Finding all logical volumes
  LV        VG            #Seg Attr   LSize  Maj Min KMaj KMin Origin
Snap%  Move Copy%  Log LV UUID
  config    TruStore-Data    1 -wi-ao  1.00G  -1  -1 253  1
                      G5XBMC-None-iIFa-16MF-UHMm-mhPg-vEF3da
  data      TruStore-Data    1 owi-d- 63.00G  -1  -1 253  3
                      xxpvao-sSsu-QnSu-bLnp-kprJ-IBEd-n1VHiV
  data_snap TruStore-Data    1 swi--- 45.00G  -1  -1 -1   -1   data
                      m4ZSZG-ba0q-Fgco-sYcy-e0DJ-V3SI-Bb0r6C
  home      TruStore-Data    1 -wi-ao 10.00G  -1  -1 253  0
                      HU7HFS-YOTs-xTwH-6Pg1-c4k0-UQOK-7O4j6X

Hopefully that is not too badly word wrapped.

> Alasdair
> --
> agk@redhat.com

Thanks
Greg
-- 
Greg Freemyer
The Norcross Group
Forensics for the 21st Century

Re: [linux-lvm] Missing link in /dev/<domain>?

[Greg Freemyer]

Alasdair,

Quick follow-up.  I said below that vgmknodes is correctly recreating
my link, but actually the symbolic link it is creating is pointing to
the non-working enty /dev/mapper/my-domain-data, not the working
-data-real entry.

Greg
On 8/11/06, Greg Freemyer <greg.freemyer@gmail.com> wrote:
> On 8/11/06, Alasdair G Kergon <agk@redhat.com> wrote:
> > On Fri, Aug 11, 2006 at 01:59:35PM -0400, Greg Freemyer wrote:
> > > my-domain-data
> > > my-domain-data-real
> >
> > > The unexpected entry is the -data-real one.
> >
> > Did you try anything with snapshots?
> >
> Yes, I routinely perform a snapshot everynight via cron.  No idea if a
> snapshot existed when the machine went down.
>
> > See what vgmknodes does.
> >
> I renamed the manually created link from data to data.tmp, then ran vgmknodes.
>
> The data link was successfully recreated.
>
> > Post the output of dmsetup info -c and lvs -va.
> >
> # dmsetup info -c
> Name             Maj Min Stat Open Targ Event  UUID
> TruStore--Data-data-real 253   2 L--w    1    1      0
> LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBxxpvaosSsuQnSubLnpkprJIBEdn1VHiV-real
> TruStore--Data-home 253   0 L--w    1    1      0
> LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBHU7HFSYOTsxTwH6Pg1c4k0UQOK7O4j6X
> TruStore--Data-data 253   3 ---w    0    0      0
> LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBxxpvaosSsuQnSubLnpkprJIBEdn1VHiV
> TruStore--Data-config 253   1 L--w    1    1      0
> LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBG5XBMCNoneiIFa16MFUHMmmhPgvEF3da
>
> # lvs -va
> File descriptor 4 left open
>     Finding all logical volumes
>   LV        VG            #Seg Attr   LSize  Maj Min KMaj KMin Origin
> Snap%  Move Copy%  Log LV UUID
>   config    TruStore-Data    1 -wi-ao  1.00G  -1  -1 253  1
>                       G5XBMC-None-iIFa-16MF-UHMm-mhPg-vEF3da
>   data      TruStore-Data    1 owi-d- 63.00G  -1  -1 253  3
>                       xxpvao-sSsu-QnSu-bLnp-kprJ-IBEd-n1VHiV
>   data_snap TruStore-Data    1 swi--- 45.00G  -1  -1 -1   -1   data
>                       m4ZSZG-ba0q-Fgco-sYcy-e0DJ-V3SI-Bb0r6C
>   home      TruStore-Data    1 -wi-ao 10.00G  -1  -1 253  0
>                       HU7HFS-YOTs-xTwH-6Pg1-c4k0-UQOK-7O4j6X
>
> Hopefully that is not too badly word wrapped.
>
> > Alasdair
> > --
> > agk@redhat.com
>
> Thanks
> Greg
> --
> Greg Freemyer
> The Norcross Group
> Forensics for the 21st Century
>


-- 
Greg Freemyer
The Norcross Group
Forensics for the 21st Century

Re: [linux-lvm] Missing link in /dev/<domain>?

[Alasdair G Kergon]

On Fri, Aug 11, 2006 at 03:38:56PM -0400, Greg Freemyer wrote:
> Name             Maj Min Stat Open Targ Event  UUID
> TruStore--Data-data-real 253   2 L--w    1    1      0
> LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBxxpvaosSsuQnSubLnpkprJIBEdn1VHiV-real
> TruStore--Data-home 253   0 L--w    1    1      0
> LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBHU7HFSYOTsxTwH6Pg1c4k0UQOK7O4j6X
> TruStore--Data-data 253   3 ---w    0    0      0
                              ^

> LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBxxpvaosSsuQnSubLnpkprJIBEdn1VHiV
> TruStore--Data-config 253   1 L--w    1    1      0
> LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBG5XBMCNoneiIFa16MFUHMmmhPgvEF3da
 
> Snap%  Move Copy%  Log LV UUID
>  config    TruStore-Data    1 -wi-ao  1.00G  -1  -1 253  1
>                      G5XBMC-None-iIFa-16MF-UHMm-mhPg-vEF3da
>  data      TruStore-Data    1 owi-d- 63.00G  -1  -1 253  3
>                      xxpvao-sSsu-QnSu-bLnp-kprJ-IBEd-n1VHiV
>  data_snap TruStore-Data    1 swi--- 45.00G  -1  -1 -1   -1   data
>                      m4ZSZG-ba0q-Fgco-sYcy-e0DJ-V3SI-Bb0r6C
>  home      TruStore-Data    1 -wi-ao 10.00G  -1  -1 253  0
>                      HU7HFS-YOTs-xTwH-6Pg1-c4k0-UQOK-7O4j6X
 
It still thinks you have a snapshot, but it's failing to activate it.
If you don't need it, try lvremoving the snapshot.

Alasdair
-- 
agk@redhat.com

Re: [linux-lvm] Missing link in /dev/<domain>?

[Greg Freemyer]

lvremove of the snapshot resolved my issue, thanks.

I'm using 2.6.16 (from SUSE) which I know is a little old.

Is the snapshot code likely to progress beyond experimental in the
vanilla kernel soon, or maybe already has?

Thanks
Greg

On 8/11/06, Alasdair G Kergon <agk@redhat.com> wrote:
> On Fri, Aug 11, 2006 at 03:38:56PM -0400, Greg Freemyer wrote:
> > Name             Maj Min Stat Open Targ Event  UUID
> > TruStore--Data-data-real 253   2 L--w    1    1      0
> > LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBxxpvaosSsuQnSubLnpkprJIBEdn1VHiV-real
> > TruStore--Data-home 253   0 L--w    1    1      0
> > LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBHU7HFSYOTsxTwH6Pg1c4k0UQOK7O4j6X
> > TruStore--Data-data 253   3 ---w    0    0      0
>                               ^
>
> > LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBxxpvaosSsuQnSubLnpkprJIBEdn1VHiV
> > TruStore--Data-config 253   1 L--w    1    1      0
> > LVM-mMDI3Wi6Av0TlwI4D905RvPDfWM3rNlBG5XBMCNoneiIFa16MFUHMmmhPgvEF3da
>
> > Snap%  Move Copy%  Log LV UUID
> >  config    TruStore-Data    1 -wi-ao  1.00G  -1  -1 253  1
> >                      G5XBMC-None-iIFa-16MF-UHMm-mhPg-vEF3da
> >  data      TruStore-Data    1 owi-d- 63.00G  -1  -1 253  3
> >                      xxpvao-sSsu-QnSu-bLnp-kprJ-IBEd-n1VHiV
> >  data_snap TruStore-Data    1 swi--- 45.00G  -1  -1 -1   -1   data
> >                      m4ZSZG-ba0q-Fgco-sYcy-e0DJ-V3SI-Bb0r6C
> >  home      TruStore-Data    1 -wi-ao 10.00G  -1  -1 253  0
> >                      HU7HFS-YOTs-xTwH-6Pg1-c4k0-UQOK-7O4j6X
>
> It still thinks you have a snapshot, but it's failing to activate it.
> If you don't need it, try lvremoving the snapshot.
>
> Alasdair
> --
> agk@redhat.com
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>


-- 
Greg Freemyer
The Norcross Group
Forensics for the 21st Century