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List:       ceph-devel
Subject:    Re: Data-at-rest compression at EC pools blueprint
From:       Samuel Just <sjust () redhat ! com>
Date:       2015-09-30 18:40:49
Message-ID: CAN=+7FUzyWRJ+PWbuJv1T2=uORFTPmr8_XRpMthAiy10oT+caQ () mail ! gmail ! com
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Seems like a reasonable start.  Quick back-of-the-envelope calculation
suggests 2k of (logical_offset, compressed_offset) pairs per 1MB of
data with 8MB/pair and 4k chunks, which is probably ok to stuff into
an xattr.  You should restructure the blueprint to make it independent
of EC.  ReplicatedPG can do this before feeding the writes to the
backend (whichever backend is used) -- the pool alignment parameter
could be set on a replicated pool to enforce aligned appends on a
compressed replicated pool.
-Sam

On Wed, Sep 30, 2015 at 8:44 AM, Igor Fedotov <ifedotov@mirantis.com> wrote:
> Folks,
>
> I've just added a blueprint about adding compression to EC pools as per our
> previous discussion.
> Please find it at
> http://tracker.ceph.com/projects/ceph/wiki/Submissions
>
> Not sure I did that in proper manner - by attaching a new file. Other
> blueprints look different at this page. Can't undo though.
> Sorry about that.
>
> And please point out different way to publish my blueprint if needed.
>
> Any way - comments and reviews on the content are welcome.
>
> Thanks.,
> Igor.
>
>
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