Hmm,
Apologies for the empty reply. Thanks for those suggestions...
I'm assuming we're talking kernel modules here, and not having vast
amounts of experience
at that I think its a little beyond me. Realistically, the majority of
the information
captured from the feed will not be needed, only high-resolution
information from when
services are invoked. I'm aiming for the angle that such information can
come from
anywhere, so long as plug-ins are written to capture it, but a good
demonstration would
be to capture ganglia's metrics.
I'm trying to get this info read into java so I can manipulate and store
it there - it
seems an implementation of rrd for java (rrd4j) should be able to read
and export rrds,
but unfortunately is in a slightly different format to ganglias (rrd
v0003). Not wanting
to write a complex modification to their converter for v0001 rrds, I'm a
little lost as
to how I can get it there.
Its slightly ironic because I am considering persisting the data to java
rrds anyway...
Ian
Seth Graham wrote:
Ben Hartshorne wrote:
On Tue, Aug 08, 2006 at 04:22:41PM +0100, Ian Wootten wrote:
I am facing a problem in that I would like short-segment up to date
information from ganglia in order to monitor services after invocation.
One method I have heard of that achieves something similar; write a
separate module that interprets the XML feed directly.
This works well, and I've done it in a single page of code so it's
simple stuff. It becomes more of a chore when you want to actually
store that data. For short periods it's fine, but if you got a lot of
machines and you don't cycle out data the database will get really big
really fast.
The other thing to consider is how often the xml updates. Clients
running gmond only report at set intervals, so if you're trying to get
information once a second you'll be unhappy with the results. This, in
combination with gmetad's write intervals, is why the rrds have the
'NaN' holes in them. Writing your own module may improve getting real
actual numbers, but it won't improve the quality of the data.
Newer versions of ganglia allow you to customize update intervals, but
on a big network setting values too frequent will generate a lot of
traffic, and probably slow the gmetad server to a crawl with all the
rrd updates.
