After rrd migration graph is not recording values

Problem

After the rrd migration, for some reason, some graphs are not recording values:

In the cmc.log, you may see these kinds of messages:

2022-04-06 13:24:41 [4] [client 1] Error accessing RRD: No DS called '12' in '/opt/omd/sites/mysite/var/check_mk/rrd/schiller/Interface_eth1-02.45.rrd'
2022-04-06 13:24:41 [4] [client 1] Error accessing RRD: No DS called '6' in '/opt/omd/sites/mysite/var/check_mk/rrd/schiller/Interface_eth1-02.45.rrd'
2022-04-06 13:24:41 [4] [client 1] Error accessing RRD: No DS called '5' in '/opt/omd/sites/mysite/var/check_mk/rrd/schiller/Interface_eth1-02.45.rrd'
2022-04-06 13:24:41 [4] [client 1] Error accessing RRD: No DS called '11' in '/opt/omd/sites/mysite/var/check_mk/rrd/schiller/Interface_eth1-02.45.rrd'

Solution

1. Change to the rrd directory.

   OMD[mysite]:~$ cd var/check_mk/rrd/<HOSTNAME>

2. How many metrics are stored in the .info file?

   OMD[mysite]:~/var/check_mk/rrd/myhost.txt$ cat Interface_2.info 
   HOST myhost
   SERVICE Interface eth0
   METRICS outqlen;in;out;inerr;inmcast;inbcast;inucast;innucast;indisc;outerr;outmcast;outbcast;outucast;outnucast;outdis

   15 Metrics are stored here
   
   

3. How many datasources do we have in the .rrd file?

   OMD[test]:~/var/check_mk/rrd/kirchner_check_mk_agent_output.txt$ rrdtool info Interface_2.rrd |grep "last_ds"
   ds[1].last_ds = "U"
   ds[2].last_ds = "U"
   ds[3].last_ds = "U"
   ds[4].last_ds = "0"
   ds[7].last_ds = "U"
   ds[8].last_ds = "U"
   ds[9].last_ds = "U"
   ds[10].last_ds = "U"
   ds[13].last_ds = "U"
   ds[14].last_ds = "U"
   ds[15].last_ds = "U"

   -->  11 Datasources are stored. As described in the cmc.log, DS 5,6,11, and 12 are missing
   
   

4. So here we have a mismatch of the number of metrics in the .info (15 Metrics ) file and the amount of Datasources (11 DS) in the .rrd file
   
   
5. We need to create the missing DS into the rrd file. 
   

   Before continuing here, please note that we do not provide support for any broken .rrd file. Please be careful and do a backup of that files beforehand. 

   1. Stop the site
      

      OMD[mysite]:~$ omd stop

   2. Create the four missing datasources

      rrdtool tune Interface_2.rrd DS:5:GAUGE:8460:0:U
      rrdtool tune Interface_2.rrd DS:6:GAUGE:8460:0:U
      rrdtool tune Interface_2.rrd DS:11:GAUGE:8460:0:U
      rrdtool tune Interface_2.rrd DS:12:GAUGE:8460:0:U

      More information about the command can be found here: https://oss.oetiker.ch/rrdtool/doc/rrdtune.en.html.
      
      

   3. Start the site

      OMD[mysite]:~$ omd start

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