From: "Piotr Dałek" <branch@predictor.org.pl>
To: ceph-devel <ceph-devel@vger.kernel.org>
Subject: Re: snapshot implementation problems/options
Date: Tue, 26 Jul 2016 07:24:21 +0200 [thread overview]
Message-ID: <20160726052421.GE658@predictor> (raw)
In-Reply-To: <CAJ4mKGbf-zvTkZaqqsZDOA=ZrCsq=WRP80DM3wQpXcOWxYX-hg@mail.gmail.com>
On Mon, Jul 25, 2016 at 07:41:53PM -0700, Gregory Farnum wrote:
> [..]
> Anyway, these are the things I'm thinking about right now and that
> we'll want to consider as we evaluate moving forward on snapshots and
> other features. If you have thoughts or design ideas, please speak up!
One thing that striked me in the past is the way the snapshot information is
kept by OSDs. In a nutshell, it's a bufferlist with pre-encoded data that
OSDs keep for entire lifetime. Once we need these data, we decode the
bufferlist. One issue is that we waste time for snapshot data decode, and
another is that we waste RAM for bufferlist itself, even when the object(s)
don't have any snashots at all.
While working on new snapshots implementation, that could be taken into
account too...
--
Piotr Dałek
branch@predictor.org.pl
http://blog.predictor.org.pl
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next prev parent reply other threads:[~2016-07-26 5:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-26 2:41 snapshot implementation problems/options Gregory Farnum
2016-07-26 5:24 ` Piotr Dałek [this message]
2016-08-01 7:48 ` Sage Weil
2016-08-01 13:52 ` Gregory Farnum
2016-08-05 9:23 ` Sage Weil
2016-08-05 22:57 ` Gregory Farnum
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