[Gluster-users] metadata for stat : Should it be identical?

Anand Avati avati at gluster.org
Fri Oct 25 20:33:57 UTC 2013

On Fri, Oct 25, 2013 at 12:51 PM, James <purpleidea at gmail.com> wrote:

> On Fri, Oct 25, 2013 at 3:18 PM, Anand Avati <avati at gluster.org> wrote:
> > In normal operations they will differ as much as the time drift between
> the
> > servers + lag in delivery/issue of write() calls on the servers. This
> delta
> > is "fixed up" by consistently returning the highest of the two mtimes
> > whenever queried.
> But lets says we have replica == 2.
> On server A this mtime is 4:45
> On server B this mtime is 4:46
> So fuse queries the times, and it returns the max, which is 4:46.
> All is good.
> Suppose now that server B is down, and the query is run again.
> It should now return 4:45, although this means that file has changed mtime.
> This could break client operations, which may care about a change in mtime.
> Note that I don't expect differences of 1 minute, but I just chose
> arbitrary values to make understanding the example easier.
> So isn't this a bug?

This is a known behavior - when a server goes down, files can witness a
changed mtime (but I don't think that is what the original post was about).
We could provide a new feature/enhancement to keep mtimes in sync with
explicit utimes() call per-write() - but that might be too expensive for
most users.

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