[Lustre-discuss] OST load distribution
Jure Pečar
pegasus at nerv.eu.org
Wed May 8 07:30:26 PDT 2013
On Wed, 8 May 2013 14:05:18 +0000
"Lee, Brett" <brett.lee at intel.com> wrote:
> The qos_threshold_rr setting dictates whether the RR or QOS algorithms are used. Setting it to 55% tells the MDS to use QOS only when the difference in OST utilization is greater than 55. You probably should go back to the default of 17% to keep OSTs balanced, unless there is a reason to trade off less equally distributed data for performance.
I noticed that lfs df -i returns same numbers for all OSTs (19%), which means that most of them hold many more smaller files than the first one.
After I set qos_threshold_rr to 55%, load on first OST slowly decreased while fs throughput remained about the same. I hope it will stay like this but will observe closely.
--
Jure Pečar
http://jure.pecar.org
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