[ClusterLabs] [Slightly OT] OCFS2 over LVM

Jorge Fábregas jorge.fabregas at gmail.com
Tue Aug 25 08:50:51 EDT 2015

On 08/24/2015 12:20 PM, Digimer wrote:
> Speaking from a gfs2 background, but assuming it's similar in concept to
> ocfs2...
> Cluster locking comes at a performance cost. All locks need to be
> coordinated between the nodes, and that will always be slower that local
> locking only. They are also far less commonly used than options like nfs.
> Using a pair of nodes with a traditional file system exported by NFS and
> made accessible by a floating (virtual) IP address gives you redundancy
> without incurring the complexity and performance overhead of cluster
> locking. Also, you won't need clvmd either. The trade-off through is
> that if/when the primary fails, the nfs daemon will appear to restart to
> the users and that may require a reconnection (not sure, I use nfs
> sparingly).
> Generally speaking, I recommend always avoiding cluster FSes unless
> they're really required. I say this as a person who uses gfs2 in every
> cluster I build, but I do so carefully and in limited uses. In my case,
> gfs2 backs ISOs and XML definition files for VMs, things that change
> rarely so cluster locking overhead is all but a non-issue, and I have to
> have DLM for clustered LVM anyway, so I've already incurred the
> complexity costs so hey, why not.

Your point is well-taken.  Thanks for the advice Digimer!


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