[Samba] Troubleshooting poor (small) random read performance -- serverid.tdb?

Jeremy Allison jra at samba.org
Thu Jun 19 15:37:30 MDT 2014

On Thu, Jun 19, 2014 at 11:52:12AM -0700, Ray Van Dolson wrote:
> Shoot, wish I'd done some Googling and stumbled across that prior to
> bumping up to RHEL7!
> With that said, here are a couple of updates:
> All configs are using "default" options plus these:
>     aio read size = 1
>     aio write size = 1
>     strict locking = no
>     use sendfile = yes
> - RHEL 7.0 with the stock Samba 4.1.1 - no significant improvement
>   observed on the application side.  smbd processes still showed very
>   high CPU utilization, system load went up to 10 but minimal disk
>   activity seen.  strace on smbd processes looked significantly
>   different from what I saw on 3.6.x.  My fu wasn't strong enough to
>   discern where most time was being spent.
> - RHEL 7.0 with Sama 4.1.8 stolen from Fedora 20 - definite improvement
>   observed.  System load stayed around 1.0 or lower and on the
>   application side we saw processing occurring at a pretty good clip,
>   though not as good as Windows.  There are parent processing nodes and
>   children processing nodes... some of the child nodes didn't get fully
>   "spun up" and were complaining about being unable to access some of
>   the data they needed.... which led us to....
> - RHEL 7.0 with Samba 4.1.8 and "locking = no" set on the share from
>   which data is being read.  Best results by far -- basically matched
>   Windows performance.  All parent and "child" nodes had their CPU's
>   fully maxed out indicating they were able to get at the data they
>   needed quickly.

So are you using "locking = no", "strict locking = no"
or "posix locking = no" ?

That's not entirely clear from your message, and would
be an interesting data point to know !



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