5 Replies Latest reply: Mar 26, 2013 3:28 PM by 906815 RSS

    Hostnames, dns, etc

    906815
      Hi,

      Everything started with the deployment of OEM GC agents on our database server boxes.

      We have Linux, Solaris - on Spark and i86..

      hosts files are in the format:

      IP....alias....FQDN

      as a result we've gotten duplication of hosts on the grid (same short names -aliases f.e "bb1").

      Commands "hostname' and "uname -a" result in alias , such as "bb1"

      Changes in hosts files are ignored -> Commands "hostname' and "uname -a" result again in alias and not in FQDN.

      After editing the hosts file - IP...FQDN...alias - the only result is to get two hosts in GC for every single server.

      Listeners are not recognized to be up.... all kind of malfunctioning.
      ---

      On the other hand - on servers with correct hosts files and commands "hostname' and "uname -a" resulting in FQDN --- we have no issues in GC - all targets are properly discovered,
      no duplications, no status misrepresentations.

      To make the story short - what could cause the hosts file to be ignored (after editing).

      (grep hosts /etc/nsswitch.conf
      # "hosts:" and "services:" in this file are used only if the
      #hosts: files dns
      hosts: cluster files dns)

      Are there any DNS settings that override the hosts file?

      Thx,

      Edited by: 903812 on Mar 21, 2013 3:15 PM

      Edited by: 903812 on Mar 21, 2013 3:15 PM
        • 1. Re: Hostnames, dns, etc
          sb92075
          903812 wrote:
          Hi,

          Everything started with the deployment of OEM GC agents on our database server boxes.

          We have Linux, Solaris - on Spark and i86..

          hosts files are in the format:

          IP....alias....FQDN

          as a result we've gotten duplication of hosts on the grid (same short names -aliases f.e "bb1").

          Commands "hostname' and "uname -a" result in alias , such as "bb1"

          Changes in hosts files are ignored -> Commands "hostname' and "uname -a" result again in alias and not in FQDN.

          After editing the hosts file - IP...FQDN...alias - the only result is to get two hosts in GC for every single server.

          Listeners are not recognized to be up.... all kind of malfunctioning.
          ---

          On the other hand - on servers with correct hosts files and commands "hostname' and "uname -a" resulting in FQDN --- we have no issues in GC - all targets are properly discovered,
          no duplications, no status misrepresentations.

          To make the story short - what could cause the hosts file to be ignored (after editing).

          (grep hosts /etc/nsswitch.conf
          # "hosts:" and "services:" in this file are used only if the
          #hosts: files dns
          hosts: cluster files dns)

          Are there any DNS settings that override the hosts file?
          not as above, but as below

          hosts: cluster dns files
          • 2. Re: Hostnames, dns, etc
            EdStevens
            903812 wrote:
            Hi,

            Everything started with the deployment of OEM GC agents on our database server boxes.

            We have Linux, Solaris - on Spark and i86..

            hosts files are in the format:

            IP....alias....FQDN

            as a result we've gotten duplication of hosts on the grid (same short names -aliases f.e "bb1").

            Commands "hostname' and "uname -a" result in alias , such as "bb1"

            Changes in hosts files are ignored -> Commands "hostname' and "uname -a" result again in alias and not in FQDN.

            After editing the hosts file - IP...FQDN...alias - the only result is to get two hosts in GC for every single server.

            Listeners are not recognized to be up.... all kind of malfunctioning.
            ---

            On the other hand - on servers with correct hosts files and commands "hostname' and "uname -a" resulting in FQDN --- we have no issues in GC - all targets are properly discovered,
            no duplications, no status misrepresentations.

            To make the story short - what could cause the hosts file to be ignored (after editing).

            (grep hosts /etc/nsswitch.conf
            # "hosts:" and "services:" in this file are used only if the
            #hosts: files dns
            hosts: cluster files dns)

            Are there any DNS settings that override the hosts file?

            Thx,

            Edited by: 903812 on Mar 21, 2013 3:15 PM

            Edited by: 903812 on Mar 21, 2013 3:15 PM
            uname does not get its information from /etc/hosts. See [url http://jblevins.org/log/hostname]this for a bit more information.

            It sounds like you might be expecting the hosts file to be used in ways that it is simply not used. It is not used for a system to identify itself. It is used by the OSI network stack to resolve a hostname to an IP address when requested to send a packet to a destination.

            Edited by: EdStevens on Mar 22, 2013 5:56 AM
            • 3. Re: Hostnames, dns, etc
              906815
              Thank you,

              To make the things more complicated I'd say that we are experiencing "issues" on our Solaris boxes, not the Linux ones.

              And to add more confusion - on 2 RAC's with 2 nodes (i386) each (identical network configs - at least on the surface) we have one node that is exhibiting issues.

              The main issue is that the listener state in OEM GC is shown as "down" (red arrow), but in reality on the box the listener is healthy and sound.

              Then we have single Solaris-11.2 box (Spark) where the listener is shown as "down" as well .

              Reconfiguring the listener from GC - replacing hostname(s) with IP or vice verse is not effective.

              Editing the hosts file led to duplicate hosts in GC - host for the new(and only) line and host for the old line (not existing anymore).

              ./agentca -d ->always leads to duplicate targets.

              I have opened a SR but for no avail so far...

              Not sure what to do next.

              Thx,
              • 4. Re: Hostnames, dns, etc
                EdStevens
                903812 wrote:
                Thank you,
                <snip>
                I have opened a SR but for no avail so far...

                Not sure what to do next.

                Thx,
                What to do next is work the SR you opened with support.
                • 5. Re: Hostnames, dns, etc
                  906815
                  Ed,

                  It is easier said than done for the SR.

                  ALL Oracle Support initiatives and suggestions led to nowhere...

                  Even after escalation I have no feedback for a week...

                  This is what I meant as "to no avail"