From: Mike Ryan <mike.ryan@inktank.com>
To: Gregory Farnum <greg@inktank.com>
Cc: ceph-devel@vger.kernel.org
Subject: Re: PG recovery reservation state chart
Date: Tue, 2 Oct 2012 13:21:59 -0700 [thread overview]
Message-ID: <20121002202159.GD8206@splice> (raw)
In-Reply-To: <CAPYLRzgU+DxNFepUY3s1PvAG-zeBxsrDrgcGUxbwTswpy6zFgA@mail.gmail.com>
On Tue, Oct 02, 2012 at 01:02:06PM -0700, Gregory Farnum wrote:
> Remote and local reservations come out of a different pool?
Yes. This simplifies deadlock prevention.
> I think I know what you're talking about here, but can you provide a
> bit more background on the reservations and stuff?
This is an attempt to limit the amount of recovery operations occurring
at the same time.
Each OSD has a finite number of reservation slots. Reservation requests
are made by PGs to the OSD. A reservation request succeeds immedately if
there are slots available. If none are available, it will succeed after
a reservation is released (freeing a slot).
Before a recovery op may proceed, the primary collects reservations from
itself and all its replicas. If one of the OSDs is busy, the reservation
process will wait until a reservation is available before continuing.
next prev parent reply other threads:[~2012-10-02 20:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-02 19:48 PG recovery reservation state chart Mike Ryan
2012-10-02 20:02 ` Gregory Farnum
2012-10-02 20:21 ` Mike Ryan [this message]
2012-10-02 20:31 ` Josh Durgin
2012-10-02 20:40 ` Mike Ryan
2012-10-02 20:35 ` Tommi Virtanen
2012-10-02 20:42 ` Mike Ryan
2012-10-02 22:00 ` Josh Durgin
2012-10-02 22:39 ` Mike Ryan
2012-10-02 21:36 ` Sage Weil
2012-10-02 21:43 ` Mike Ryan
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