Hi,
may i ask which part of codes within ceph deal with the distribution
of workloads among the OSDs? i am interested in ceph's source codes
and want to understand that part of codes.
Thanks,
Sheng
On Tue, Sep 11, 2012 at 11:51 AM, Tommi Virtanen <tv@xxxxxxxxxxx> wrote:
> On Mon, Sep 10, 2012 at 8:54 PM, sheng qiu <herbert1984106@xxxxxxxxx> wrote:
>> i have a simple question.
>> for distribution workload among OSDs, does ceph do any online modeling
>> for OSDs, i.e. collect the online IO latency and try to distribute
>> more workloads to lower latency OSDs? or only based on
>> capacity/utilization balance?
>
> I've heard this question now several times. Ceph does not contain the
> logic to adjust OSD weights based on such measurements. Ceph will
> collect some measurements that are useful for this ("perf counters",
> mostly).
>
> For a holistic systems view, the metrics Ceph collects aren't enough.
> You also want to take into account things like CPU load, available
> memory, hardware temperature sensors, network link utilization,
> network error rate, etc. And once you start looking at that angle, you
> realize that this is a completely generic "machine health" indicator,
> where Ceph is just one of the data sources.
>
> Hence, I view this as something that ultimately consumes more
> information than just Ceph. Ceph should play nice, and both feed
> information into such a system, and let the system set OSD weights;
> but I do believe it belongs outside of Ceph core.
--
Sheng Qiu
Texas A & M University
Room 332B Wisenbaker
email: herbert1984106@xxxxxxxxx
College Station, TX 77843-3259
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