[rrd-users] Inquiring on how to ease disk io (linux).

[Raimund Berger]

Hi

I'm currently evaluating collectd on linux for monitoring (with
rrdtool backend of course), and while the default 10s update interval
is pretty cool, as the number of monitored systems increases the
server's disks start to rattle noticably. Quite understandably so I
guess, as rrdtool isn't meant to provide (sequential disk) caching
solutions like sql stuff usually sports.

Right now, I'm testing a workaround by stack mounting a tmpfs over the
real rrd database directory via aufs, which pleasantly resolves the
disk io issue. It has drawbacks though:

* as data is written only to the tmpfs, all of it written since the
  last mount/disk copy is going to be lost on crash/power outage
* those stacking fs (aufs, unionfs) apparently provide no means to
  automatically sync back data at specified intervals.

That's at least how I now see it, so my solution is not yet completely
satisfactory.

Question hence, did anybody here already run into and maybe tackle a
similar issue in a better way? If so, I'd sure appreciate some hints.

Thanks, R.