[mythtv-users] Mysql max-connections and bind-address

[Mark Perkins]

> >> On 26 Sep 2013, at 7:40 pm, "Simon Hobson" <linux at thehobsons.co.uk>
> wrote:
> ....
> >> There is a memory requirement per available connection, which according
> tomysqltuner is currently 4.6M for my setup. That means 100 connections
> would eat up getting on for half a gig of ram on top of your global memory
> useage.
> >
> > [Mark] If I read my output correctly I have 48.7M per thread so
> > multiply your figure by 10 would be somewhere north of 5G. If I recall
> > correctly I have 2G RAM and 2G swap partition so I guess I have a
> > problem there already. Although the database is on a SSD so that
> > probably explains why I don't see any performance impacts (up until
> > when the SSD fails from excessive reads / writes maybe?)
> 
> Note that the output from mysqltuner is a "worst case maximum"
> (basically, all the connections are actively issuing requests, all are
using join
> buffers, all are using sort buffers, etc.).  Your actual use will vary
(and for
> dedicated (for MythTV) MySQL engine, and for the MythTV case, where
> most connections are more "idle" than "active", your actual use will be
far
> less).
> 
> There are some specific advice for MySQL tuning on the MythTV wiki pages
> at: http://www.mythtv.org/wiki/Tune_MySQL but note that some of the
> advice may not apply to your particular usage (as with much else, MySQL
> tuning is well understood only by those that well understand it; for
others, it
> is closer to magic).
> 
> Gary

[Mark] Just to provide a bit of an update on my mysql performance and to
close out my original post. I had intended to post the mysqltuner.pl test
results earlier but I would forget and reboot for some reason or another and
loose the history. Output is attached as a txt file but key points are that
highest usage of available connections in the last week (a quiet week really
I guess) has been 54. Might be worth noting that I have 8 tuners (4x2) so I
assume that if you have fewer tuners there would be fewer connections
required. Everything else appears to be in order except table cache hit rate
of 0% - however I have not noticed any sluggishness in performance so am not
concerned at this stage.

Thanks again to everyone for their advice and input.