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Re: [Linux-cluster] mixing OS versions?


On 24/04/14 17:29, Alan Brown wrote:
On 30/03/14 12:34, Steven Whitehouse wrote:

Well that is not entirely true. We have done a great deal of
investigation into this issue. We do test quotas (among many other
things) on each release to ensure that they are working. Our tests have
all passed correctly, and to date you have provided the only report of
this particular issue via our support team. So it is certainly not
something that lots of people are hitting.

Someone else reported it on this list (on centos), so we're not an isolated case.

We do now have a good idea of where the issue is. However it is clear
that simply exceeding quotas is not enough to trigger it. Instead quotas
need to be exceeded in a particular way.

My suspicion is that it's some kind of interaction between quotas and NFS, but it'd be good if you could provide a fuller explanation.

Yes, thats what we thought to start with... however that turned out to be a bit of a red herring. Or at least the issue has nothing specifically to do with NFS. The problem was related to when quota was exceeded, and specifically what operation was in progress. You could write to files as often as you wanted to, and exceeding quota would be handled correctly. The problem was a specific code path within the inode creation code, if it didn't result in quota being exceeded on that one specific code path, then everything would work as expected.

Also, quite often when the problem did appear, it did not actually trigger a problem until later, making it difficult to track down.

You are correct that someone else reported the issue on the list, however I'm not aware of any other reports beyond yours and theirs. Also, this was specific to certain versions of GFS2, and not something that relates to all versions.

The upstream patch is here:

It should be available in RHEL shortly - please ping support via the ticket for updates,


Returning to the original point however, it is certainly not recommended
to have mixed RHEL or CentOS versions running in the same cluster. It is
much better to keep everything the same, even though the GFS2 on-disk
format has not changed between the versions.

More specfically (for those who are curious): Whilst the on-disk format has not changed between EL5 and EL6, the way that RH cluster members communicate with each other has.

I ran a quick test some time back and the 2 different OS cluster versions didn't see each other for LAN heartbeating.

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