[Gluster-users] Detecting split brain

[Pranith Kumar K]

On 12/01/2011 11:33 PM, anthony garnier wrote:
> So if I understand well, a value different than 0sAAAAAAAAAAAAAAAA for 
> the attribute trusted.afr.poolsave-client-0 indicate split brain.
>
> Thx
>
> > Date: Thu, 1 Dec 2011 11:23:29 -0500
> > From: jdarcy at redhat.com
> > To: sokar6012 at hotmail.com
> > CC: gluster-users at gluster.org
> > Subject: Re: [Gluster-users] Detecting split brain
> >
> > On Thu, 1 Dec 2011 16:00:09 +0000
> > anthony garnier <sokar6012 at hotmail.com> wrote:
> >
> > >
> > > Hi,
> > >
> > > I got a lot of files with attributes : 0sAAAAAAAAAAAAAAAAA
> > >
> > > Serv 1 :
> > > # file: tbo_rmr_globale_log_11-04-07_15h43m48s.log
> > > trusted.afr.poolsave-client-0=0sAAAAAAAAAAAAAAAA
> > > trusted.afr.poolsave-client-1=0sAAAAAAAAAAAAAAAA
> > > trusted.gfid=0sfm7CRROuQ4+wuQfmHjFCdg==
> > >
> > > Serv 2 :
> > > # file: tbo_rmr_globale_log_11-04-07_15h43m48s.log
> > > trusted.afr.poolsave-client-0=0sAAAAAAAAAAAAAAAA
> > > trusted.afr.poolsave-client-1=0sAAAAAAAAAAAAAAAA
> > > trusted.gfid=0sfm7CRROuQ4+wuQfmHjFCdg==
> > >
> > > Does it mean that those files need Self-Healing ? I use GlusterFS
> > > 3.2.3
> >
> > This is actually normal. For some reason that would probably make me
> > throw up if I knew it, getfattr misreports 0x000000000000000000000000
> > as 0sAAAAAAAAAAAAAAAA (which would be 0x404040404040404040404040) if
> > you don't give it the "-e hex" flag. The value is actually three
> > four-byte integers, and if they're zero it means there are no pending
> > operations. Any *other* value is likely to indicate split brain.
>
>
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Small Correction:
Different value than 0sAAA.. means there are pending operations.
If you dump the values with -e hex option and there should be 24 digits, 
first 8 represent pending operations on the data of the files 
(write/truncate). next 8 represent pending operations on metadata 
(permissions, ownership etc) next 8 represent pending operations on 
entry (creation/deletion/rename of a file inside that directory). Now if 
both data/metadata/entry digits are non-zero on a file then that will be 
split-brain.
Example:
Data split-brain:
  trusted.afr.poolsave-client-0=0s000000010000000000000000
  trusted.afr.poolsave-client-1=0s000000200000000000000000

Thanks
Pranith
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