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| johanroux |
 Posted: Wed Apr 21, 2010 7:14 am Post subject: MQ and DNS servers |
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Novice
Joined: 21 Apr 2010
Posts: 10
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Hi all, I really hope someone can provide some info to help with this. We are on zOS1.10 and MQ V6. We have a problem where the primary DNS server for an LPAR was shut down. MQ did not seem to like this one bit and couldn't get any channels started while it was down. Aftes some time MQ was bounced and some channels could start. Once the primary DNS server was restarted all channels started immediately and without any other issues. According to the Network team there are no differences between the primary and secondary DNS server and theoretically MQ should not have had a problem. The OS is able to resolve both the primary and secondary servers without problem. This issue is receiving very high focus at the moment because the customer is (rightly so) worried about what would happen if the primary server went down during online day. So my question is what could cause MQ to lose the plot so completely? In MQ itself we only specify a PORT number so I'm really baffled as to what could cause this.
Any help would be appreciated. |
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| bruce2359 |
| Posted: Wed Apr 21, 2010 7:21 am Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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| Quote: |
| ...where the primary DNS server for an LPAR was shut down. ...So my question is what could cause MQ to lose the plot so completely? In MQ itself we only specify a PORT number so I'm really baffled as to what could cause this. |
What did you learn from errors logged in the CHIN a/s for the qmgr?
What have you/your network admins done to enable the alternate DNS server?
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| Vitor |
| Posted: Wed Apr 21, 2010 7:23 am Post subject: Re: MQ and DNS servers |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| johanroux wrote: |
| In MQ itself we only specify a PORT number so I'm really baffled as to what could cause this. |
In any sender channel you'll be specifying a connection name, which will not only be a port but also an IP address (either numeric or a DNS name).
The obvious question is this: when you couldn't get the channels to start what did the logs say? What error were they throwing?
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Honesty is the best policy.
Insanity is the best defence. |
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| johanroux |
| Posted: Thu Apr 22, 2010 12:20 am Post subject: |
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Novice
Joined: 21 Apr 2010
Posts: 10
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| Well this is where it gets strange. There are NO error messages produced. For example the one channel was started at 04:37 and until 10:24 when the CHIN was bounced there are no error messages or anything else for that channel. The channel stays in BIND status throughout. My thinking on this is that it cannot really be an MQ problem and that it must be something like NET or TCPIP not resolving the switch from the primary to secondary server correctly. Unfortunately MQ is the one showing all the issues so I've basically been handed the investigation. |
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| Vitor |
| Posted: Thu Apr 22, 2010 5:25 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| johanroux wrote: |
| My thinking on this is that it cannot really be an MQ problem and that it must be something like NET or TCPIP not resolving the switch from the primary to secondary server correctly. |
| johanroux wrote: |
| Unfortunately MQ is the one showing all the issues so I've basically been handed the investigation. |
Get the network people to switch from primary to secondary again "to help you reproduce the problem". If it fails again, use telnet or other network tools to sniff the connection and throw it back at them. If it doesn't fail, blame "transient connection issues".
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Honesty is the best policy.
Insanity is the best defence. |
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| bruce2359 |
| Posted: Thu Apr 22, 2010 5:38 am Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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| Get the network people to switch from primary to secondary again "to help you reproduce the problem". If it fails again, use telnet or other network tools to sniff the connection and throw it back at them. If it doesn't fail, blame "transient connection issues". |
And once the network folks demonstrate that killing the primary DNS does not gracefully enable the secondary for network users, get them to implement auto-recovery procedures.
I, too, agree that MQ is the victim, not the culprit here.
_________________
I like deadlines. I like to wave as they pass by.
ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| johanroux |
| Posted: Fri Apr 23, 2010 2:06 am Post subject: |
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Novice
Joined: 21 Apr 2010
Posts: 10
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| Would it be necessary to bounce the CHIN to pick up the secondary if the switch happens while MQ is up? |
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| exerk |
| Posted: Fri Apr 23, 2010 2:15 am Post subject: |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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| johanroux wrote: |
| Would it be necessary to bounce the CHIN to pick up the secondary if the switch happens while MQ is up? |
Not if the networks people have done their job properly...
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It's puzzling, I don't think I've ever seen anything quite like this before...and it's hard to soar like an eagle when you're surrounded by turkeys. |
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| johanroux |
| Posted: Fri Apr 23, 2010 2:38 am Post subject: |
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Novice
Joined: 21 Apr 2010
Posts: 10
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One more thing to muddy the waters even further or possibly clear it up completely.
Apparently MVS will wait 30 seconds while trying the primary DNS server before trying the secondary. It will apparently do this for EVERY call trying to go out. So I think this might be where MQ loses the plot.. |
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| bruce2359 |
| Posted: Fri Apr 23, 2010 5:15 am Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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TCPIP on mvs can be customized to do this whenever and how often you choose. Your network folks (should) know this.
_________________
I like deadlines. I like to wave as they pass by.
ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| bruce2359 |
| Posted: Fri Apr 23, 2010 5:23 am Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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Moved to Mainframe and CICS.
_________________
I like deadlines. I like to wave as they pass by.
ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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