[Drbd-dev] DRBD Trim/discard

Eric Wheeler drbd at ew.ewheeler.org
Thu Sep 26 21:01:40 CEST 2013

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 

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!


[1] http://lists.linbit.com/pipermail/drbd-user/2012-March/017987.html

Eric Wheeler
eWheeler Inc.

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