[rrd-developers] two problem about RRD UPDATE

[Florian Forster]

Hi Lily,

On Sun, Mar 15, 2009 at 10:39:37AM +0800, lily wrote:
> How can I keep the data in memory? Use the mmap ? Is upgrade the
> version to 1.3.6 wil be OK  or I have to something in my code ?

basically, all you have to do is have more memory - the operating system
should do the rest..

> My rrdtool is the 1.2.27, I don't know if I upgrade my version to
> 1.3.6, Is there some *compatibility *problem ?

Version 1.3 introduces a changed file format. It can still work with RRD
files created by version 1.2, but not the other way around.

> > > You did mount with `noatime' and `nodiratime', right? While this doesn't
> > > perform miracles, it'll certainly increase performance some percent..
> 
> Yes , I did not do that . But if I do that , I don't have the access
> time , rigth ?

Uhm, yes.. That's why it's called `NOatime'.. What do you need the
`atime' for? Are you sure you don't confuse this with the `mtime'?

I've heard of a system which relied on `atime' to clean up dynamically
created files (they were using the file system as some kind of cache,
really). When IO killed that system, they started deleting files a fixed
time after they were created (possibly recreating busy items/files),
which improved performance A LOT.

> Now I reduce the number of the file from 12K to 8K , I have not
> encountered the problem yet. So I think the reason is the high load .

I guess that your 12k files just do not fit into your 4 GBytes of RAM
and those 8k files to. I'd interpret this observation as indication that
more RAM is the easiest way out of your performance problems.

Regards,
-octo
-- 
Florian octo Forster
Hacker in training
GnuPG: 0x91523C3D
http://verplant.org/
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