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MQSeries.net Forum Index » General IBM MQ Support » channel bufssent bufsrcvd attribute, what if they're diff?

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belchman
PostPosted: Thu Jul 06, 2006 4:18 am    Post subject: channel bufssent bufsrcvd attribute, what if they're diff? Reply with quote

Partisan

Joined: 31 Mar 2006
Posts: 386
Location: Ohio, USA

If I have a sender channel that has been running for a month and the value for bufssent is 1.15 times higher than the value for bufsrcvd, is this indicative of some sort of problem?

actual values are:

bufssent=185385
bufsrcvd=160968

Can someone explain what MQ is sending in these buffers and how they are used?

Thanks.
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wschutz
PostPosted: Thu Jul 06, 2006 11:04 am    Post subject: Reply with quote

Jedi Knight

Joined: 02 Jun 2005
Posts: 3316
Location: IBM (retired)

Are you having any problem? Or is this just curiosity?

When sending messages which are larger than the tcp transmission buffer, you will see this imbalance in the send/receive counts.
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belchman
PostPosted: Thu Jul 06, 2006 11:26 am    Post subject: Reply with quote

Partisan

Joined: 31 Mar 2006
Posts: 386
Location: Ohio, USA

We are having a problem, but I also like to learn more while I solve the problem.

Problem:

We have a B2B that involves QM to QM over leased line. Our sender channel intermittently slows down which causes the xmit queue to momentarily build depth. This causes monitor alarms to go off. 7000 messages per day are passed over this sender channel in batches of undetermined size (variable).

I was thinking that the bufssent bufsrcvd difference could point to network retries.

Thanks
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Nigelg
PostPosted: Fri Jul 07, 2006 1:03 am    Post subject: Reply with quote

Grand Master

Joined: 02 Aug 2004
Posts: 1046

I do not think that the difference would mean network retries.

AFter initial channel negotiation, BUFSRCVD will be one per batch
BUFSSENT will be more than one per batch, if the number of msgs sent in the batch is more than one and the total size of the msgs is less than 32K, the send buffer size.
Imagine that the msgs are 32000 bytes eachm and that there are 10 on the xmitq.
Ater channel negotiation, probably 2 buffers each way, the 10 msgs will be sent in 10 transmissions, with the batch confirm piggybacked to the last msg. During a batch, no transmissins are returned by the RCVR.
When the confirm flow is received, the RCVR will send 1 transmission back.

So, in this imaginary channel after 1 batch, BUFSSENT will be 13, and BUFSRCVD will be 3.

In your case, since the ratio is much less than that, it is likely that the batches contain less msgs, or multiple msgs fit into a single transmission.

I recommend you remove the hair trigger from your alarms.
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belchman
PostPosted: Fri Jul 07, 2006 3:35 am    Post subject: Reply with quote

Partisan

Joined: 31 Mar 2006
Posts: 386
Location: Ohio, USA

Very Informative, thank you very much Nigel.
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