Re: default filestore max sync interval

[Stefan Priebe <s.priebe@profihost.ag>]

Hi Dan,

Am 29.04.2014 22:10, schrieb Dan Van Der Ster:
> Hi all,
> Why is the default max sync interval only 5 seconds?
>
> Today we realized what a huge difference that increasing this to 30 or 60s can do for the small write latency. Basically, with a 5s interval our 4k write latency is above 30-35ms and once we increase it to 30s we can get under 10ms (using spinning disks for journal and data.)
>
> See the attached plot for the affect of this on a running cluster (the plot shows the max, avg, min write latency from a short rados bench every 10 mins). The change from 5s to 60s was applied at noon today. (And our journals are large enough, don't worry).
>
> In the interest of having sensible defaults, is there any reason not to increase this to 30s?

I was playing with them too but didn't get any viewable results. How do 
you get / graph the ceph latency?

Greets,
Stefan