[Gluster-devel] Network Outage - Expected Behaviour?

[Gordan Bobic]

On Thu, 9 Jul 2009 08:32:12 -0700 (PDT), Martin Fick <mogulguy at yahoo.com>
wrote:
> --- On Thu, 7/9/09, Gordan Bobic <gordan at bobich.net> wrote:
>> What is the expected behaviour of
>> gluster client when servers disappear
>> (due to a short network outage) and re-appear? For example,
>> say there are
>> servers A and B, and client C. A goes away (e.g. pull the
>> network cable).
>> Timeout occurs, client continues using B. A returns without
>> glusterfsd
>> being restarted or the client glusterfs being restarted.
>> 
>> Does the client periodically re-scan for presence of
>> servers that dropped
>> out? Or does the client have to be restarted to notice that
>> a server has
>> returned?
> 
> I would like to add the question, what happens to locks
> when the server goes down?

If I remember correctly from previous conversation:
The primary server (first one listed) is always the lock "master". Locks
get replicated to slaves. If one of the secondaries goes down, it doesn't
affect anything. If the primary goes down, the lock mastering gets moved to
the next server listed (ordering matters, and all clients must list servers
in the same order!). Locks don't get migrated back, and if we run out of
servers (go full circle), I think all locks status is lost. Whether this
has changed recently (or will change soon to deal with that edge case), I
don't know.

> Are they dropped when it returns?  What if a client goes down with locks,
do
> they timeout?

That is a good question, I don't believe I have heard an explicit answer to
this.

Note: Forwarded to list since Martin's reply didn't go to the list. I hope
that's OK, since it seemed like a list question.

Gordan