For a while now I've noticed a behavior in the Distribution Manager component I can't really explain, hopefully someone here can point me in the right direction.

Environment: SCCM 2012 R2 CU4 with a single primary site and approximately 200 distribution points (about 15 of which are Pull). Most of them have a latency above 100ms, some even exceeding 500ms (I know.. but you have to work with what you've got right?).

During certain times Distribution Manager will simply not distribute any content even though there are .PKN files in its Inbox. When checking distmgr.log I can see the component is still responsive and iterating over all our DPs and doing some ConfigureDP and ConfigurePXE tasks (all happening in a single thread). However it just doesn't pick up on any new distribution jobs, there are no "Inbox change notification occurred" messages coming in even though there are clearly new files in the inbox.

DPJobManager shows no other jobs are running, so we're not running into any limits.

This usually takes up to an hour or two, after which it will resume normal operation and quickly start processing all the missed jobs. Also it doesn't happen at specific times, it seems to be completely random but persistent in that it happens approximately once every day.

Now I'd like to know what's causing this issue, is this some expected behavior where the component will just take a timeout or are we experiencing a bug of some sorts? I can remember seeing this even back when we were still running R2 RTM so it's not like a new thing that just started happening.

Hi,

Check your DP properities, sc

Under DP Properties check Schedule and Rate limits tab. Check if you have you configured any settings over there.

Unfortunately that's not it.

We of course have some DPs with schedules but the vast majority is open 24/7 with no rate limits.

Edit:

It seems we're experiencing the issue again right now and I suspect there is something wrong with the inbox change notifications not being delivered to the distribution manager component. The last entry in distmgr.log is the following from 55 minutes ago:

Sleeping for 60 minutes before content cleanup task starts.

However since then we got at least 6 new files in the inbox without any sort of reaction from distmgr. Shouldn't there be a notification sent to the component whenever a file gets added? IIRC this is sent by Windows itself, is there any way to check the subscribers?

• Edited by oLee88 4 minutes ago

Unfortunately that's not it.

We of course have some DPs with schedules but the vast majority is open 24/7 with no rate limits.

Edit:

It seems we're experiencing the issue again right now and I suspect there is something wrong with the inbox change notifications not being delivered to the distribution manager component. The last entry in distmgr.log is the following from 55 minutes ago:

Sleeping for 60 minutes before content cleanup task starts.

However since then we got at least 6 new files in the inbox without any sort of reaction from distmgr. Shouldn't there be a notification sent to the component whenever a file gets added? IIRC this is sent by Windows itself, is there any way to check the subscribers?

• Edited by oLee88 Tuesday, July 21, 2015 7:43 AM

However since then we got at least 6 new files in the inbox without any sort of reaction from distmgr. Shouldn't there be a notification sent to the component whenever a file gets added?  - That will happen automatically, you cannot do it manually. Can you confirm that for 60 minutes there are absolutely no entries in distmgr.log file ?.

Yes, I can confirm that. Actually nothing happened for about 110 minutes (except for the usual 60 minute cleanup interval). After that I figured restarting the component might help, which was a bad idea as it wasn't able to stop and stayed in the 'stopping' state for nearly 10 minutes before we tried restarting the SMS Executive Service. This didn't work out either (hung in 'stopping' state as well) so we had to reboot the server.

After that distmgr came back to life and processed all pending jobs flawlessly.

Having kept an eye on the log file for the last couple of hours during normal operation, I can clearly see the following entry each time a new file gets added to the inbox:

Inbox change notification occurred, will end sleep in 5 seconds for required processing.

During the downtimes we're experiencing, this message doesn't arrive. After an hour or two the component starts up again and processes all files in the inbox.

I'm not sure if this is happening because a new notification get's through (which would indicate an issue with Windows not sending notifications for a while) or if the component simply didn't process the incoming notifications because some thread was stuck (which would indicate an issue with SCCM). Seeing as I wasn't able to restart the component during one such phase I'm inclined to believe it's the second possibility - I'm just not sure how to troubleshoot this.

Yes, I know this is an old post, but Im trying to clean them up. Did you solve this problem, if so what was the solution?

Since no one has answer this post, I recommend opening  a support case with Microsoft Customer Support Services (CSS) as they can work with you to solve this problem.