[Drbd-dev] DRBD Trim/discard

Lars Ellenberg lars.ellenberg at linbit.com
Fri Sep 27 14:47:48 CEST 2013

On Thu, Sep 26, 2013 at 12:01:40PM -0700, Eric Wheeler wrote:
> Hello all,
> We would like to run DRBD backed by thin-provisioned volumes (think
> ZFS or dm-thinp) which require discard support to dereference unused
> block allocations.  (I searched around for DRBD trim/discard support
> with little commentary except the reference [1] below which does not
> apply to our use case.)
> Is discard support on the roadmap?
> What are the technical considerations for implementation?
> I'm guessing this would be a relatively simple patch, just need to
> add a discard flag to the wire protocol and pass that to the backing
> device (after calculating the metadata offset, if any).
> If you can comment on the desired implementation of such a feature
> and point me in the right direction I may be able to write a patch
> and test.
> Any help you can offer would be greatly appreciated!

We are integrating DISCARD / TRIM support into our currently pending
DRBD 8.4.4 release, right now.
Code changes expected to be pushed with the RC2, latest early next week.

Thanks for testing and feedback,



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