[ClusterLabs] Question on sharing data with DRDB

[Digimer]

Note;

  Cluster filesystems are amazing if you need them, and to be avoided if
at all possible. The overhead from the cluster locking hurts performance
quite a lot, and adds a non-trivial layer of complexity.

  I say this as someone who has used dual-primary DRBD with GFS2 for
many years.

  To expand on why you can't use something like ext4; Non-cluster-aware
file systems expect all changes to the backing device to go through it.
So there's no mechanism to tell the FS on one node that blocks have
changed because of actions on another node. Likewise, they have no
mechanism to coordinate sane and safe access to blocks. These mechanisms
are exactly what makes a cluster FS what it is.

digimer

On 2019-03-20 11:52 a.m., Emmanuel Gelati wrote:
> If you need to access from both nodes, you need to use primary/primary
> mode in drbd
> 
> Il giorno mer 20 mar 2019 alle ore 16:51 JCA <1.41421 at gmail.com
> <mailto:1.41421 at gmail.com>> ha scritto:
> 
>     OK, thanks. Yet another thing I was not aware of in the clustering
>     world :-(
> 
>     On Wed, Mar 20, 2019 at 9:41 AM Valentin Vidic
>     <Valentin.Vidic at carnet.hr <mailto:Valentin.Vidic at carnet.hr>> wrote:
> 
>         On Wed, Mar 20, 2019 at 09:36:58AM -0600, JCA wrote:
>         >      # pcs -f fs_cfg resource create TestFS Filesystem
>         device="/dev/drbd1"
>         > directory="/tmp/Testing"
>         >         fstype="ext4"
> 
>         ext4 can only be mounted on one node at a time. If you need to
>         access
>         files on both nodes at the same time than a cluster filesystem
>         should
>         be used (GFS2, OCFS2).
> 
>         -- 
>         Valentin
>         _______________________________________________
>         Manage your subscription:
>         https://lists.clusterlabs.org/mailman/listinfo/users
> 
>         ClusterLabs home: https://www.clusterlabs.org/
> 
>     _______________________________________________
>     Manage your subscription:
>     https://lists.clusterlabs.org/mailman/listinfo/users
> 
>     ClusterLabs home: https://www.clusterlabs.org/
> 
> 
> 
> -- 
>   .~.
>   /V\
>  //  \\
> /(   )\
> ^`~'^
> 
> _______________________________________________
> Manage your subscription:
> https://lists.clusterlabs.org/mailman/listinfo/users
> 
> ClusterLabs home: https://www.clusterlabs.org/
> 


-- 
Digimer
Papers and Projects: https://alteeve.com/w/
"I am, somehow, less interested in the weight and convolutions of
Einstein’s brain than in the near certainty that people of equal talent
have lived and died in cotton fields and sweatshops." - Stephen Jay Gould