[rrd-developers] [Ganglia-developers] Integrating rrdcached with Ganglia

Daniel.Pocock at barclayscapital.com Daniel.Pocock at barclayscapital.com
Mon Sep 29 17:34:42 CEST 2008


> -----Original Message-----
> From: Pocock, Daniel: IT (LDN) 
> Sent: 29 September 2008 13:28
> To: bernard at vanhpc.org; rrd-developers at lists.oetiker.ch; 
> ganglia-developers at lists.sourceforge.net
> Subject: Re: [Ganglia-developers] Integrating rrdcached with Ganglia
> > http://ganglia.wiki.sourceforge.net/rrdcached_integration
> > 
> > Comments/feedbacks welcome.
> Thanks for this - I decided to try it:
> - RHEL5
> - 64 bit
> - APR 1.2.7
> - rrdtool 1.3.2 + rrdcached patch from here:
>     http://dist.rufus.net/~kbrint/rrdcached/rrdcache.patch
> - Ganglia 3.1.0
> gmetad stores the data and IO levels are definitely better.
> However, when I display the web page with graphs for every 
> farm, rrdcached crashes, SEGV:
> (gdb) bt
> #0  0x0000003312077b60 in memcpy () from /lib64/libc.so.6
> #1  0x00002aaaaaae1633 in rrd_write () from /usr/lib64/librrd.so.4
> #2  0x00002aaaaaae5e10 in rrd_lock () from /usr/lib64/librrd.so.4
> #3  0x00002aaaaaae69e2 in rrd_lock () from /usr/lib64/librrd.so.4
> #4  0x00002aaaaaae7cfb in rrd_lock () from /usr/lib64/librrd.so.4
> #5  0x0000000000405113 in ?? ()
> #6  0x00000033134062f7 in start_thread () from /lib64/libpthread.so.0
> #7  0x00000033120ce85d in clone () from /lib64/libc.so.6
> The problem is reproducable every time I refresh 
> http://my-server/ganglia/

I've upgraded to 1.3.3 (the patch applies with 1 reject, which is only
the copyright message) and installed the debug symbols and found that
each time this error occurs, rrd_update is trying to update an RRD file
that is smaller than the expected size (i.e. smaller than the other RRD
files in the same directory)

I haven't yet established whether the RRD files were created earlier
with the wrong size, or if they have somehow been truncated during the

The whole directory tree was empty before I started doing these tests,
so the RRD files have definitely been created with rrdtool 1.3.

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