[rrd-developers] Problems with rrdcached and RRDs::graph

[kevin brintnall]

On Fri, Jan 29, 2010 at 06:02:52AM -0800, SaschaTen wrote:
> 
> Hello,
> I try to use rrdcached-daemon in version 1.4.2, the caching and updateing of
> the rrd-files run well. The cached-deamon was started with the command:
> "rrdcached -l 192.168.30.13.1:1234 -b /opt/rrd -w 600 -f 3600 -j
> /opt/rrd/cache -F -t 10".

Hi,

I think you are running into a surprise introduced in r1928:

1928>  However, when talking to a remote daemon, absolute path names
1928>  are not allowed, since path name translation is done by the
1928>  server (relative to the base directory).

Try using a Unix socket..  It should work fine.

> After this I want to use the cached feature in combination with drawing a
> graph. If I understand the methode right, I can send RRD an flag, that it
> have to import the data for the rrdfile before drawing the graph, this is
> possible in the CLI with the parameter "--daemon (unixsocket or ip:port)",
> but the Perl-packet RRDs.pm seem to have no possibility for this parameter
> in the function graph.
> 
> Now I tried to test the CLI for the rrdtool, the "normal" command works well
> "rrdtool graph /srv/www/htdocs/pic.png -a PNG --start 1263375151 --end
> 1263378751 DEF:inoctets=/opt/rrd/some.rrd:input:AVERAGE
> CDEF:inbits=inoctets,8,*,1.024,/,1.024,/ LINE:inbits#FF0000" the graph was
> correctly painted.
> 
> When trying to us the flush function for the data: "rrdtool graph
> /srv/www/htdocs/pic.png -a PNG --start 1263375151 --end 1263378751
> DEF:inoctets=/opt/rrd/some.rrd:input:AVERAGE
> CDEF:inbits=inoctets,8,*,1.024,/,1.024,/ LINE:inbits#FF0000 --daemon
> 192.168.30.13:1234" the result is "ERROR: rrdc_flush (/opt/rrd/some.rrd)
> failed with status -1." it failed. This error code doesn't really help me.

I think we should do a better job of passing the failure messages from the
daemon back to RRD's error string.  I'll look into that.

> The last thing I tried was to run a flush manuel, but the same problem
> occurred :
>   rrdtest:~ # telnet 192.168.30.13 1234
>   Trying 192.168.30.13...
>   Connected to 192.168.30.13.
>   Escape character is '^]'.
>   STATS
>   9 Statistics follow
>   QueueLength: 0
>   UpdatesReceived: 326937
>   FlushesReceived: 10
>   UpdatesWritten: 166110
>   DataSetsWritten: 273969
>   TreeNodesNumber: 0

Note that your tree is empty at this time..  TreeNodesNumber = 0 ...

>   TreeDepth: 0
>   JournalBytes: 38482393
>   JournalRotate: 1221
>   FLUSHALL
>   0 Started flush.
>   FLUSH some.rrd
>   -1 No such file: /opt/rrd/some.rrd.

... this explains why the FLUSH failed.  Although it exists on the file
system, it is not presently cached in rrdcached.

If you try again after a successful UPDATE, it should work just fine.

-- 
 kevin brintnall =~ /kbrint at rufus.net/


>   QUITE
>   rrdtest:~ # ls -la /opt/rrd
>   total 268
>   drwxr-xr-x 3 root root 4096 Jan 13 12:49 .
>   drwx------ 10 root root 4096 Jan 13 12:48 ..
>   drwxr-xr-x 2 root root 4096 Jan 13 12:48 cache
>   -rw-r--r-- 1 root root 257896 Jan 13 12:49 some.rrd
> 
> Have I made an error in my installation or is this behavioure normal? On the
> Webside I can't find a hint how to solve this problem.
> Is the "--daemon"-function implementet in the RRDs.pm?
> 
> Regards
> Sascha 
> -- 
> View this message in context: http://n2.nabble.com/Problems-with-rrdcached-and-RRDs-graph-tp4480089p4480089.html
> Sent from the RRDtool Developers Mailinglist mailing list archive at Nabble.com.
> 
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