22 Feb
2017
22 Feb
'17
11:11 a.m.
ID: 8077
Title: New option --split-rrds for --rrd-convert, converts PNP storage type
Component: config
Level: 2
Class: New feature
Version: 1.2.5i6
Check_MK has now a new builtin function for converting legacy-style PNP RRDs
from storage type <tt>SINGLE</tt>, which had been the default for many years,
to <tt>MULTIPLE</tt>, which is the current default since about three years.
<tt>SINGLE</tt> means that all metrics of one host or service are stored
in a single round robin database, whereas with <tt>MULTIPLE</tt> each RRD
does contain only one single datasource.
Performance tests have revealed that - other then one might guess -
<tt>MULTIPLE</tt> is not significantly slower. But it has the advantage
that new datasources can be added on the fly. This is often needed when new
versions of Check_MK introduce new metrics. For that reason Check_MK only
fully supports storage type <tt>MULTIPLE</tt>. When using the Check_MK
Micro Core then you <b>have</b> to convert to <tt>MULTIPLE</tt>,
if you do
not want to loose your historic metrics, because the CMC does not support
<tt>SINGLE</tt> at all.
Converting RRDs - essentially splitting them up - can be done with PNP4Nagios'
shipped utility <tt>lib/pnp4nagios/rrd_convert.pl</tt>, but that is a bit
clumsy to use and very slow. If you have thousands of hosts the conversion
can take many days.
For that reason Check_MK now can do the splitting into multiple RRDs during the
process of the RRD conversion. This is not only simpler for you. It is also
much faster because it uses the native C code of the recent RRDTool. This
is how to do the conversion. We assume that you are using Nagios as your
monitoring core:
<ol>
<li>Make a backup of the directory
<tt>var/pnp4nagios/perfdata</tt>.</li>
<li>Stop the <tt>npcd</tt>. This avoids RRD updates while the conversion
is in progress:
C+:
OM:omd stop npcd
C-:
</li>
<li>Start the conversion. The option <tt>-v</tt> selects verbose
output:
C+:
OM:cmk -v --convert-rrds --split-rrds
C-:
</li>
<li>Edit the file <tt>etc/pnp4nagios/process_perfdata.cfg</tt> and
change the storage type:
F+:etc/pnp4nagios/process_perfdata.cfg
RRD_STORAGE_TYPE = MULTIPLE
F-:
</li>
<li>Start the <tt>npcd</tt> again:
C+:
OM:omd start npcd
C-:
</li>
</ol>
<b>Notes:</b>
<ul>
<li>You can specify host names as arguments to <tt>cmk
--convert-rrds</tt>. The conversion
will then only be done for these hosts. But when you start <tt>ncpd</tt> again
and only
some of the hosts are being converted, then hosts that do not match the storage type
in <tt>process_perfdata.cfg</tt> will loose their RRD data.</li>
<li>The splitting and the conversion to the RRD configuration that is setup via
WATO
with the rulesets <i>Configuration of RRD databases of hosts</i> and
<i>Configuration of RRD databases of services</i> will be done at the same
time. There
is no way to just split. But the <i>Default</i> configuration of PNP4Nagios
and of
WATO for the RRDs is the same, so if you have changed neither, you essentiall will
just split.</li>
<li>Check_MK will <b>not create any backups of any files!</b> Failed
modifications, unlucky RRD
configuration and software bugs can lead to data loss. Make sure you have a
backup.</li>
</ul>