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| ph_dap |
 Posted: Mon Nov 15, 2004 12:52 am Post subject: Channel status stopped |
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Novice
Joined: 19 Nov 2003
Posts: 14
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Can someone enlight me on the following situation.
I have a connection between three unix servers running MQ Series 5.0.
Server A connects to C, server B connects to C. We have stopped MQ Series on servers A and B and then performed a reboot of both servers. In the meantime, nothing has been done on server C.
How come I get the two sending channels on server C to resp. server A and B, having status "stopped". I would have expected the channels to reconnect when the servers A and B were available again.
What can I do to prevent this from happening?
Can a channel get status stopped when it does not get a response within a certain amount of time?
Any answer highly appreciated. |
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| csmith28 |
| Posted: Mon Nov 15, 2004 1:08 am Post subject: |
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Grand Master
Joined: 15 Jul 2003
Posts: 1196
Location: Arizona
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In earlier versions of MQ the bouncing an MQManager or the server that hosted an MQManager would reset the status of the channel to "inactive" and the channels would be allowed to restart if they were properly configured to TRIGGER.
I believe it was version 5.2 and later when they started recording the status of a channel so it would survive a reboot of the host or a cycling of the MQManager. So if you stop a channel and bounce the MQManager or the server the status is still stopped. You will have to manually restart the channels.
| Quote: |
| What can I do to prevent this from happening? |
In the future if you want the channels to restart as a result of TRIGGERING use the:
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| stop chl(CHANNEL.NAME) status(inactive) |
command to stop the channels before rebooting/bouncing the MQMGR.
The only drawback with this is, if a message/s is placed on the XMITQ that meets the TRIGGER criteria between the time you issue the stop chl command and the time that you issue the endmqm/shutdown command the channel will restart.
| Quote: |
| Can a channel get status stopped when it does not get a response within a certain amount of time? |
No, if a Sender Channel does not receive a response from the remote MCA it will usually go into a RETRY Status. The only time a Sender Channel will go into a STOPPED status is if a stop chl command is issued against said channel without specifying a status other than STOPPED.
Note if you issue a stop chl command against a channel and do not specify a status(XXXX) STOPPED is assumed.
Also, except under very limited circumstances you should never issue a stop chl command against an RCVR channel. If you do you will not be able to start the remote SDR channel until a start chl is issued.
stop chl can be issued against any channel except a CLNTCONN and once a channel is in a STOPPED status it can only be restarted by issuing start chl command manually.
See page 331 of the current WMQ5.3 Command Reference Guide.
You may also want to have a look at the WMQ Intercommunications Guide.
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| Nigelg |
| Posted: Mon Nov 15, 2004 2:44 am Post subject: |
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Grand Master
Joined: 02 Aug 2004
Posts: 1046
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| Quote: |
The only drawback with this is, if a message/s is placed on the XMITQ that meets the TRIGGER criteria between the time you issue the stop chl command and the time that you issue the endmqm/shutdown command the channel will restart.
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No. A channel will not trigger start from STOPPED
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The only time a Sender Channel will go into a STOPPED status is if a stop chl command is issued against said channel without specifying a status other than STOPPED.
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One other time, when a channel has reached the end of its SHORTRTY and LONGRTY attempts.
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.. you should never issue a stop chl command against an RCVR channel. If you do you will not be able to start the remote SDR channel until a start chl is issued.
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No. STOP CHL on a RCVR puts it into INACTIVE status, i.e. no status. |
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| PeterPotkay |
| Posted: Mon Nov 15, 2004 4:56 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| Nigelg wrote: |
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The only time a Sender Channel will go into a STOPPED status is if a stop chl command is issued against said channel without specifying a status other than STOPPED.
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One other time, when a channel has reached the end of its SHORTRTY and LONGRTY attempts.
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And if the remote MCA can't put the message, because the remote DLQ filled up, or there is no DLQ defined on the remote side (  ), the SNDR channel will also stop.
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Peter Potkay
Keep Calm and MQ On |
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| Nigelg |
| Posted: Mon Nov 15, 2004 5:52 am Post subject: |
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Grand Master
Joined: 02 Aug 2004
Posts: 1046
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| In the situations that Peter describes above, the channel will stop, but the status will not be STOPPED. It will be PAUSED for MRRTY * MRTMR milliseconds, and then it will be RETRYING. |
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| PeterPotkay |
| Posted: Mon Nov 15, 2004 6:05 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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From the Intercommunication Guide:
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We recommend that you define a dead-letter queue for each queue manager. If you do not, and the MCA is unable to put a message, it is left on the transmission queue and the channel is stopped.
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If the dead-letter queue is not available, the sending MCA leaves the
message on the transmission queue, and the channel stops. On a fast
channel, nonpersistent messages that cannot be written to a dead-letter
queue are lost.
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I must admit I haven't tried this, but the above, and everything I have heard on the subject, indicates a channel will be stopped in this scenario.
Also, I thought only RCVR type channels are PAUSED while the RCVR MCA is waiting for the Message Retry Interval. During this pause, the SNDR side shows RUNNING. SNDR channel cant be in a paused state.
I am saying the Channel will be STOPPED after the (message retry interval X message retry count) has been exhausted, and there is no DLQ, or no more room in the DLQ.
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Peter Potkay
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| Nigelg |
| Posted: Mon Nov 15, 2004 6:46 am Post subject: |
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Grand Master
Joined: 02 Aug 2004
Posts: 1046
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Peter, you are right about the PAUSED status; only RCVR channels can become PAUSED, sorry about that.
However, if the destination queue on the remote qmgr is full or PUT(DISABLED), or there is no DLQ, or the DLQ is full, i.e. if the persistent msg cannot be put to the dest queue, then the channel goes into RETRYING, not STOPPED, and becomes INDOUBT(YES).
I have just tested this.
You get some msgs in the qmgr error logs:
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AMQ9527: Cannot send message through channel 'NG1.NG2.000'.
EXPLANATION:
The channel has closed because the remote queue manager cannot receive a
message.
...
AMQ9506: Message receipt confirmation failed.
EXPLANATION:
Channel 'NG1.NG2.000' has ended because the remote queue manager did not accept
the last batch of messages.
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| PeterPotkay |
| Posted: Mon Nov 15, 2004 6:48 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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Huh. Looks like the manuals need to be more explicit. "stopped" does not mean STOPPED! 
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Peter Potkay
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| fjb_saper |
| Posted: Mon Nov 15, 2004 11:11 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Peter, If you don't do anything to remedy the problem wouldn't the channel go into STOPPED mode at the end of the maxretry ?
F.J. |
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| PeterPotkay |
| Posted: Mon Nov 15, 2004 11:21 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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Yes, that point was made in Nigel's first reply.
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Peter Potkay
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| csmith28 |
| Posted: Mon Nov 15, 2004 3:00 pm Post subject: |
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Grand Master
Joined: 15 Jul 2003
Posts: 1196
Location: Arizona
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| csmith28 wrote: |
The only drawback with this is, if a message/s is placed on the XMITQ that meets the TRIGGER criteria between the time you issue the stop chl command and the time that you issue the endmqm/shutdown command the channel will restart.
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No. A channel will not trigger start from STOPPED
Yes it will if you specify status(inactive). Which is what I specified in the above post.
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| csmith28 |
| Posted: Mon Nov 15, 2004 4:45 pm Post subject: |
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Grand Master
Joined: 15 Jul 2003
Posts: 1196
Location: Arizona
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I stand corrected, perhaps I should have inserted an "under normal circumstances" when refering to the STOPPPED status.
STOPPED
This state can be caused by one of the following:
v Channel manually stopped
A user has entered a stop channel command against this
channel.
v Retry limit reached
DISPLAY CHSTATUS
Chapter 2. The MQSC commands 201
The MCA has reached the limit of retry attempts at establishing
a connection. No further attempt will be made to establish a
connection automatically.
A channel in this state can be restarted only by issuing the START
CHANNEL command, or starting the MCA program in an
operating-system dependent manner.
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| Nigelg |
| Posted: Tue Nov 16, 2004 1:21 am Post subject: |
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Grand Master
Joined: 02 Aug 2004
Posts: 1046
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| Sorry Chris, I missed the STATUS(INACTIVE) argument in the STOP CHL command in your post. |
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| root |
| Posted: Mon Apr 18, 2005 7:13 am Post subject: I'm at IBM System Admin 2 class |
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Novice
Joined: 23 Sep 2004
Posts: 13
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My instructor also incorrectly believed that the sender channel would go into stopped. I have personally seen the receiver go paused and the sender go retrying. The sender would eventually go to stopped after the retry interval. The manuals are so unclear that even my instructor had it wrong.  Also I don't believe the paused status applies to the mainframe / Z/OS
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