RAFT and CTDB

[Michael Adam]

On 2014-11-17 at 13:20 -0800, Richard Sharpe wrote:
> On Sun, Nov 16, 2014 at 11:41 PM, Volker Lendecke
> <Volker.Lendecke at sernet.de> wrote:
> > On Sat, Nov 15, 2014 at 10:31:30AM -0800, Richard Sharpe wrote:
> >>
> >> At SDC you mentioned that you have an implementation of RAFT and I
> >> assumed, perhaps incorrectly, that you were thinking of using RAFT to
> >> manage things like recovery in CTDB.
> >>
> >> Can you tell me more about your ideas in this regard and point me at any code?
> >
> > It's not finished yet, sorry. I have the basic algorithm and
> > configuration changes done, but log compaction is still
> > missing, so this is nothing for general consumption yet.
> >
> > Apart from that, I want to have a dbwrap_raft eventually,
> > the main goal is to meet the persistence requirements that resilient
> > and persistent file handles need.
> >
> > What would your project be?
> 
> Well, I have to get CTDB working with a clustered file system that
> does not currently support fcntl locks :-(

You don't necessarily need to.
CTDB only ues the fcntl lock for the recovery lock file
which is its means for split brain prevention.

It runs without a recovery lock file.
But then you should try to implement split brain prevention for
ctdb differently. I think we still need good hooks in ctdb for
mechanisms other than the recovey lock.

Cheers - Michael
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