[linux-lvm] pvresize will cause a meta-data corruption with error message "Error writing device at 4096 length 512"

[Gang He]

Hello David,

Based on the information from Heming, do you think this is a new bug? Or we can fix it with the existing patches.
Now, the user want to restore the LVM2 meta-data back to the original status, do you have any suggestions?

Thanks
Gang

> -----Original Message-----
> From: David Teigland [mailto:teigland at redhat.com]
> Sent: 2019年10月11日 23:14
> To: Heming Zhao <heming.zhao at suse.com>
> Cc: linux-lvm at redhat.com; Gang He <GHe at suse.com>
> Subject: Re: [linux-lvm] pvresize will cause a meta-data corruption with error
> message "Error writing device at 4096 length 512"
> 
> On Fri, Oct 11, 2019 at 08:11:29AM +0000, Heming Zhao wrote:
> 
> > I analyze this issue for some days. It looks a new bug.
> 
> Yes, thanks for the thorough analysis.
> 
> > In user machine, this write action was failed, the PV header data
> > (first
> > 4K) save in bcache (cache->errored list), and then write (by
> > bcache_flush) to another disk (f748).
> 
> It looks like we need to get rid of cache->errored completely.
> 
> > If dev_write_bytes failed, the bcache never clean last_byte. and the
> > fd is closed at same time, but cache->errored still have errored fd's data.
> > later lvm open new disk, the fd may reuse the old-errored fd number,
> > error data will be written when later lvm call bcache_flush.
> 
> That's a bad bug.
> 
> > 2> duplicated pv header.
> >     as <1> description, fc68 metadata was overwritten to f748.
> >     this cause by lvm bug (I said in <1>).
> >
> > 3> device not correct
> >     I don't know why the disk
> scsi-360060e80072a670000302a670000fc68 has below wrong metadata:
> >
> > pre_pvr/scsi-360060e80072a670000302a670000fc68
> > (please also read the comments in below metadata area.) ```
> >      vgpocdbcdb1_r2 {
> >          id = "PWd17E-xxx-oANHbq"
> >          seqno = 20
> >          format = "lvm2"
> >          status = ["RESIZEABLE", "READ", "WRITE"]
> >          flags = []
> >          extent_size = 65536
> >          max_lv = 0
> >          max_pv = 0
> >          metadata_copies = 0
> >
> >          physical_volumes {
> >
> >              pv0 {
> >                  id = "3KTOW5-xxxx-8g0Rf2"
> >                  device =
> "/dev/disk/by-id/scsi-360060e80072a660000302a660000f768"
> >
> Wrong!! ^^^^^
> >                           I don't know why there is f768, please ask
> customer
> >                  status = ["ALLOCATABLE"]
> >                  flags = []
> >                  dev_size = 860160
> >                  pe_start = 2048
> >                  pe_count = 13
> >              }
> >          }
> > ```
> >     fc68 => f768  the 'c' (b1100) change to '7' (b0111).
> >     maybe disk bit overturn, maybe lvm has bug. I don't know & have no
> idea.
> 
> Is scsi-360060e80072a660000302a660000f768 the correct device for PVID
> 3KTOW5...?  If so, then it's consistent.  If not, then I suspect this is a result of
> duplicating the PVID on multiple devices above.
> 
> 
> > On 9/11/19 5:17 PM, Gang He wrote:
> > > Hello List,
> > >
> > > Our user encountered a meta-data corruption problem, when run
> pvresize command after upgrading to LVM2 v2.02.180 from v2.02.120.
> > >
> > > The details are as below,
> > > we have following environment:
> > > - Storage: HP XP7 (SAN) - LUN's are presented to ESX via RDM
> > > - VMWare ESXi 6.5
> > > - SLES 12 SP 4 Guest
> > >
> > > Resize happened this way (is our standard way since years) - however
> > > - this is our first resize after upgrading SLES 12 SP3 to SLES 12 SP4 - until
> this upgrade, we never had a problem like this:
> > > - split continous access on storage box, resize lun on XP7
> > > - recreate ca on XP7
> > > - scan on ESX
> > > - rescan-scsi-bus.sh -s on SLES VM
> > > - pvresize  ( at this step the error happened)
> > >
> > > huns1vdb01:~ # pvresize
> > > /dev/disk/by-id/scsi-360060e80072a660000302a6600003274
> >
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