[rrd-users] Performance over NFS

Tobias Oetiker tobi at oetiker.ch
Sun Dec 6 14:14:29 CET 2009

Hi Simon,

try disabeling mmap io

also try exporting nfs with the async option ... less of a data
integrity guarantee, but it should be faster ...


> Unfortunately, it's such a common term that I can't find anything
> particularly useful via searches.
> I'm collecting data on one box (a gateway router), and graphing on
> another box - with the directory holding the rrd files exported by
> NFS from the gateway. Unfortunately, while it seemed to work when I
> first set it up, it's now giving very poor performance - system
> upgrades have changed the setup from NFSv3 over UDP to V4 over TCP
> (if I remember the details correctly).
> The box doing the graphing is running Debian Etch and rrd version
> 1.2.15-0.3. /etc/fstab contains :
> w.x.y.z:/var/rrd  /gate  nfs  ro,soft  0  0
> The gateway doing the data collection is running Debian Lenny and rrd
> version 1.3.1-4. /etc/exports contains :
> /var/rrd  a.b.c.d(ro,subtree_check,all_squash,anonuid=1000,anongid=1000)
> The main rrd file that's giving problems is 22M byte in size and
> contains 510 data sources, with eight aggregations (Average and Max
> for four time periods/resolutions). Some graphs only use a couple of
> data sources, one frequently used one uses nearly 200 (in and out
> traffic for just under 100 addresses in a stacked graph), one
> (infrequently used for good reason) graphs 508 sources (in and out
> traffic for 254 addresses).
> The rrdtool processes end up spending significant amounts of time
> with ps showing them in state "rpc_wa" or "sync_p" (and I've just
> seen on in state "get_re"). It's not too bad if only one person is
> generating graphs (and waiting for them), but once or twice I've seen
> people being impatient and the box gets bogged down (not to mention
> swapping heavily) with a dozen of more rrdtool processes running.
> Even just one patient user can get the load average up into the teens.
> Can anyone give me some hints or pointers on this ?

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

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