[Gluster-devel] Issues with fallocate, discard and zerofill

[Vijay Bellur]

On 08/14/2013 12:11 PM, Anand Avati wrote:
> Shishir,
> Is this in reference to the dht open file rebalance (of replaying the
> operations to the destination server)? I am assuming so, as that is
> something which has to be handled.
>
> The other question is how should fallocate/discard be handled by
> self-heal in AFR. I'm not sure how important it is, but will be
> certainly good to bounce some ideas off here. Maybe we should implement
> a fiemap fop to query extents/holes and replay them in the other serverl?

That is one possibility.

A few other related issues to be implemented/pondered over:

- fallocate/discard/zerofill awareness needs to be built in changelog 
xlator too. fallocate/discard and zerofill in its current form are not 
logged by changelog.

- With geo-replication, what should be the behaviour of 
fallocate/discard on the slave? This could be similar to the guarantee 
provided with self-heal.

- Impact of fallocate/discard on quota enforcement and marker accounting.

-Vijay

>
> Avati
>
>
>
> On Tue, Aug 13, 2013 at 10:49 PM, Bharata B Rao <bharata.rao at gmail.com
> <mailto:bharata.rao at gmail.com>> wrote:
>
>     Hi Avati, Brian,
>
>     During the recently held gluster meetup, Shishir mentioned about a
>     potential problem (related to fd migration etc) in the zerofill
>     implementation (http://review.gluster.org/#/c/5327/) and also
>     mentioned that same/similar issues are present with fallocate and
>     discard implementations. Since zerofill has been modelled on
>     fallocate/discard, I was wondering if it would be possible to address
>     these issues in fallocate/discard first so that we could potentially
>     follow the same in zerofill implementation.
>
>     Regards,
>     Bharata.
>     --
>     http://raobharata.wordpress.com/
>
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