ROCKERDUCK Increased Messages in Queue

Over the past week we’ve noticed a larger than normal queue size on ROCKERDUCK. On our Exchange servers we strive to keep queues under 50 message at any given time which roughly equates to about 1-5 seconds of delivery time. However this week we received alerts from our monitoring of queues reaching 150 messages and staying rather “large” for the entire day. The larger queue size would only increase delivery time to 15-30 seconds, but was still above our desired values. Upon researching and testing we’ve discovered the root issue.

Microsoft has an undocumented/secret new XML value for Hub servers which limits the number of concurrent deliveries for a mailbox that appeared in SP1 that you can only find by searching the error from the delivery queue.

http://blogs.technet.com/b/exchange/archive/2011/04/11/store-driver-fault-isolation-improvements-in-exchange-2010-sp1.aspx

Essentially since SP1 the HUB servers were only allowed one current message delivery per recipient

We’ve increased the delivery from 1 concurrent delivery to 3 concurrent deliveries and have not received any new alerts.

Travis Sheldon
VP, Network Operations, ExchangeDefender
(877) 546-0316 x757
travis@ownwebnow.com