[rrd-users] Sanity checks on Buffer Cache and I/O at peak aggregation times

[Tobias Oetiker]

Derek,

Yesterday Derek Haynes wrote:

> Steve,
>
> > Which OS are you using?  If you're using a 64bit Linux then you'll get better memory handling and use with >4GB of memory.
>
> Linux 64 bit (Ubuntu).
>
> > Also, are you using rrdcached?  This can make a significant benefit on disk IO if you tune it aggressively.
>
> We've started using it on a small sample of files - working well.
> Another big advantage I see with RRDCached is the ability to spread
> out the updates around peak aggregation times (like the 00:00 UTC).
> I'm still not clear on why there is an increase in reads during those
> times.

the os operates on whole blocks, so unless a complete block is
being updates it has to be read in first unless it is still in
cache.

cheers
tobi

> -Derek
>
>
> On Sun, Sep 18, 2011 at 3:13 PM, Steve Shipway <s.shipway at auckland.ac.nz> wrote:
> > Which OS are you using?  If you're using a 64bit Linux then you'll get better memory handling and use with >4GB of memory.
> >
> > Also, are you using rrdcached?  This can make a significant benefit on disk IO if you tune it aggressively.
> >
> > Steve
> >
> >
> > Steve Shipway
> > ITS Unix Services Design Lead
> > University of Auckland, New Zealand
> > Floor 1, 58 Symonds Street, Auckland
> > Phone: +64 (0)9 3737599 ext 86487
> > DDI: +64 (0)9 924 6487
> > Mobile: +64 (0)21 753 189
> > Email: s.shipway at auckland.ac.nz
> > ? Please consider the environment before printing this e-mail
> >
> >
>
>
>
>

-- 
Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch tobi at oetiker.ch ++41 62 775 9902 / sb: -9900