[Gluster-users] Detecting split brain

[Pranith Kumar K]

On 12/05/2011 08:07 PM, anthony garnier wrote:
> thank you for  your answer.
> A last question for you, on some directory I got a little difference 
> when I display extended attribute :
>
> getfattr -d -m "trusted*" -e hex *
>
> Server1 # file: yvask300
> trusted.gfid=0x433c796513864672871226072825336f
> trusted.glusterfs.dht=0x00000001000000007fffffffffffffff
>
> Server2 # file: yvask300
> trusted.gfid=0x433c796513864672871226072825336f
> trusted.glusterfs.dht=0x00000001000000007fffffffffffffff
>
>
> Server3 # file: yvask300
> trusted.afr.poolsave-client-2=0x000000000000000002000000
> trusted.afr.poolsave-client-3=0x000000000000000002000000
> trusted.gfid=0x433c796513864672871226072825336f
> trusted.glusterfs.dht=0x0000000100000000000000007ffffffe
>
> Server4 # # file: yvask300
> trusted.afr.poolsave-client-2=0x000000000000000002000000
> trusted.afr.poolsave-client-3=0x000000000000000002000000
> trusted.gfid=0x433c796513864672871226072825336f
> trusted.glusterfs.dht=0x0000000100000000000000007ffffffe
>
> why  the attribute "trusted.afr.VOLNAME-client-X" is not displayed on 
> Server 1 & 2 ?
>
>
> Thx for your help.
>
> ------------------------------------------------------------------------
> Date: Fri, 2 Dec 2011 08:59:48 +0530
> From: pranithk at gluster.com
> To: sokar6012 at hotmail.com
> CC: jdarcy at redhat.com; gluster-users at gluster.org
> Subject: Re: [Gluster-users] Detecting split brain
>
> 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 <mailto:jdarcy at redhat.com>
>     > To: sokar6012 at hotmail.com <mailto:sokar6012 at hotmail.com>
>     > CC: gluster-users at gluster.org <mailto: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>
>     <mailto: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

The xattrs are set on need basis so no xattr means all zeros.

Thanks
Pranith
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