[Gluster-users] On making ctime generator enabled by default in stack

Vijay Bellur vbellur at redhat.com
Tue Nov 6 04:27:46 UTC 2018

On Mon, Nov 5, 2018 at 7:56 PM Raghavendra Gowdappa <rgowdapp at redhat.com>

> All,
> There is a patch [1] from Kotresh, which makes ctime generator as default
> in stack. Currently ctime generator is being recommended only for usecases
> where ctime is important (like for Elasticsearch). However, a reliable
> (c)(m)time can fix many consistency issues within glusterfs stack too.
> These are issues with caching layers having stale (meta)data [2][3][4].
> Basically just like applications, components within glusterfs stack too
> need a time to find out which among racing ops (like write, stat, etc) has
> latest (meta)data.
> Also note that a consistent (c)(m)time is not an optional feature, but
> instead forms the core of the infrastructure. So, I am proposing to merge
> this patch. If you've any objections, please voice out before Nov 13, 2018
> (a week from today).
> As to the existing known issues/limitations with ctime generator, my
> conversations with Kotresh, revealed following:
> * Potential performance degradation (we don't yet have data to
> conclusively prove it, preliminary basic tests from Kotresh didn't indicate
> a significant perf drop).

Do we have this data captured somewhere? If not, would it be possible to
share that data here?

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