[Linux-cluster] GFS2 over NFS4

[Thorvald Hallvardsson]

Hi guys,

I need some help and answers related to share GFS2 file system over NFS. I
have read the RH documentation but still some things are a bit unclear to
me.

First of all I need to build a POC for the shared storage cluster which
initially will contain 3 nodes in the storage cluster. This is all going to
run as a VM environment on Hyper-V. Generally the idea is to share virtual
VHDX across 3 nodes, put LVM and GFS2 on top of it and then share it via
NFS to the clients. I have got the initial cluster built on Centos 7 using
pacemaker. I generally followed RH docs to build it so I ended up with the
simple GFS2 cluster and pacemaker managing fencing and floating VIP
resource.

Now I'm wondering about the NFS. RedHat documentation is a bit conflicting
or rather unclear in some places and I found quite few manuals on the
internet about similar configuration and generally some of them suggest to
mount the NFS share on the clients with nolock option RH docs mention local
flock and I got confused about what supposed to be where. Of course I don't
know if my understanding is correct but the reason to "disable" NFS locking
is because GFS2 is already doing it anyway via DLM so there is no need for
NFS to do same thing what eventually mean that I will have some sort of
double locking mechanism in place. So first question is where I suppose to
setup locks or rather no locks and how the export should look like ?

Second thing is I was thinking about going a step forward and use NFS4 for
the exports. However from what I have read about NFS4 it does locking by
default and there is no way to disable them. Does that mean NFS4 is not
suitable in this case at all ?

That's all for now.

I appreciate your help.

Thank you.
TH
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