From: Wido den Hollander <wido@42on.com>
To: zou wonder <wonder.zou@gmail.com>, ceph-devel@vger.kernel.org
Subject: Re: What the ceph do when detecting one OSD overloaded?
Date: Fri, 06 Jun 2014 10:27:54 +0200 [thread overview]
Message-ID: <53917B8A.4000204@42on.com> (raw)
In-Reply-To: <CAOXjUBxhgB4L7PNdAcYhbFx8LCvW8eJ7Qj1vRbYn=aCfjGroBg@mail.gmail.com>
On 06/06/2014 10:14 AM, zou wonder wrote:
> Hi buddies,
>
> I am doing investigation on Ceph and Swift,and I am newbie to Ceph.
>
> I am unclear to the behaviour of the Ceph when there is overload situation.
> According to the doc, when Ceph do CRUSH, if it find the OSD is overload,
> it will skip it to select the other OSD. It means if the OSD don't get
> overloaded
> the object should be put in this OSD. So how about the original on put on
> this OSD when it is not get overloaded?
> Can we read it ? When doing CRUSH , the OSD will be skip.
>
CRUSH will not take any performance characteristics into account. If a
OSD is 100% utilized it will still be selected by CRUSH.
Keep in mind however that Block Devices are striped in 4MB chunks and
the same happens for Objects stored via the RADOS Gateway.
> If my understanding is wrong, please correct me.
>
> Best Regards,
> zou
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--
Wido den Hollander
42on B.V.
Ceph trainer and consultant
Phone: +31 (0)20 700 9902
Skype: contact42on
next prev parent reply other threads:[~2014-06-06 8:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-06 8:14 What the ceph do when detecting one OSD overloaded? zou wonder
2014-06-06 8:27 ` Wido den Hollander [this message]
2014-06-06 9:27 ` zou wonder
2014-06-06 10:35 ` Wido den Hollander
2014-06-06 15:46 ` Sage Weil
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