[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

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