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Date: Fri, 27 Sep 2013 14:47:48 +0200
From: Lars Ellenberg <lars.ellenberg@linbit.com>
To: drbd-dev@lists.linbit.com
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Subject: Re: [Drbd-dev] DRBD Trim/discard
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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,

Cheers,

	Lars