[Lustre-discuss] write RPC & congestion

[Kevin Van Maren]

Oleg Drokin wrote:
>> I don't have everything setup right now in our test environment but with a little effort I could setup a similar test if your wondering about something specific.
>>     
>
> Would be interesting to confirm the amount of RPCs actually being processed on the server at any one time, I think.
> Did you try the direct IO too? Some older version of lustre used to send all outstanding directio RPCs in parallel, so if you did your IO as just a single direct IO write, the latency of that write should be around a couple of RTTs. I think that we still do this even in 1.8.5, so it would make an interesting comparison.
>   

You probably want to look at the brw_stats for a single client NID to do 
that.  Unless you are running 1.8.5, check out the patch in Bug 23827 
(and maybe 23826).

Kevin