[Gluster-Maintainers] Release 5: New option noatime

[Niels de Vos]

On Fri, Sep 28, 2018 at 10:07:58AM +0530, Amar Tumballi wrote:
> On Thu, Sep 27, 2018 at 6:40 PM Shyam Ranganathan <srangana at redhat.com>
> wrote:
> 
> > On 09/27/2018 09:08 AM, Shyam Ranganathan wrote:
> > > Writing this to solicit opinions on merging this [1] change that
> > > introduces an option late in the release cycle.
> > >
> > > I went through the code, and most changes are standard option handling
> > > and basic xlator scaffolding, other than the change in posix xlator code
> > > that handles the flag to not set atime and the code in utime xlator that
> > > conditionally sets the flag. (of which IMO the latter is more important
> > > than the former, as posix is just acting on the flag).
> > >
> > > The option if enabled would hence not update atime for the following
> > > FOPs, opendir, open, read, and would continue updating atime on the
> > > following FOPs fallocate and zerofill (which also update mtime, so the
> > > AFR self heal on time change would kick in anyways).
> > >
> > > As the option suggests, with it enables atime is almost meaningless and
> > > hence it almost does not matter where we update it and where not. Just
> > > considering the problem where atime changes cause AFR to trigger a heal,
> > > and the FOPs above that strictly only change atime handled with this
> > > option, I am looking at this as functionally workable.
> > >
> >
> 
> Thanks for all these details, Shyam! Helps many to understand what the
> feature is.
> 
> 
> > > So IMO we can accept this even though it is late, but would like to hear
> > > from others if this needs to be deferred till release-6.
> > >
> >
> 
> I am all for accepting this for glusterfs-5.0! Two reasons, in one of the
> quick setup we tried, it helped to get elastic search run smoothly on
> glusterfs mounts. 2nd, we did hear from Anuradha/Ram in another email
> thread (Cloudsync with AFR) that it helped them in solving the issue.
> 
> This particular patch makes the overhead of ctime feature much much lesser!

This seems like a bugfix and not really so much of a feature. From the
description of the patch and in the related BZs I could not find how to
set the option (or is it automatic?). Including it should be fine, but
the documentation/design/spec for the ctime xlator should be ammended as
well.
... which I could not find in https://github.com/gluster/glusterfs-specs

Niels