High CPU Usage in Exchange User Monitor Tool and High RPC Average Latency in Exchange 2007, How to Fix and How We Did It?

Last couple of weeks we have faced several strange issues on our company’s Microsoft Exchange 2007 environment (Yes, still 2007, not the latest version). It took some time to investigate, analyze, find a solution and fix it without distracting mail services for any of  the around 1300 users. Always high CPU usage in Exchange user monitor tool by only particular user, high RPC average latency, very slow in downloading and updating new mails in MS outlook and some email related strange problems from particular user, are the major issues we faced. I explain more about the issues and how we fixed it in this article.

We had a clue on these issues after using Exchange user monitor tool, obviously we can guess that something is wrong when an user consumes more than 95% of CPU ( exchange store CPU) all the time. But really we could not finalize that this particular user is causing other all mail issues. Anyhow, it is fixed and Exchange 2007 is working fine now.

high cpu usage on exmon exchange 2007

We faced two types of  issues related to mail, one from Exchange 2007 mailbox server and other one from particular user side.

Issues on Exchange

1) Particular user consumes almost full store CPU which is really not healthy for the environment.

2) RPC average latency is very high, it used to touch 100% continuously. Somewhere in Microsoft site I read that if it goes more than 20%, then something seriously wrong in exchange environment.

3) Downloading and updating inbox in MS outlook became very slow. It used to show hours to download/update emails which are just in KB size.

4) Delay in sending and receiving emails.


Issues from Particular user side

The user is having 4 ActiveSync enabled ( iPhone, iPad and Android) devices with Windows 7 –Outlook 2010 laptop.

1) Calendar entries are not synced properly among the devices.

2) If an appointment in calendar is postponed by his secretary or himself to other date, it will be okay for some time, but comes back to previous date again later.

3) Recurring reminders pop up even after deleting them.

4) Most of the contacts synced from Exchange server show email address with IMCEAEX prefix, that looks really weird without proper email domain address.

5) Always some complaints about his contacts and calendar entries in devices or laptop.

Since only this user is facing these types of issues, though there are more mail users with several ActiveSync enabled devices, we could suspect that something is wrong with particular user’s mailbox or configuration or one of the devices.

Also, we can’t just disable or remove ActiveSync devices from this user account for testing purpose, because he is an high profile user in company.

To see whether his mail box is healthy and not corrupted, we decided to move the mailbox from one storage to other one with skip corrupted messages option. Believe me, that solved the all issues.


How to Fix It?

To remove the corrupted items from particular mailbox, we have decided to move mailbox to other storage with ‘skip corrupted messages’ option. This will skip the corrupted entries in mailbox which is digestible in our case compared to the issues we were facing. Better take a full mailbox backup before doing this move.

move mailbox

Our all issues of high CPU usage in exchange user monitor tool, RPC average latency and particular mail box issues are solved once we move the mailbox from existing storage group to other one. Below is the screenshot of current good RPC Averaged Latency counter on Exchange 2007, earlier it used to be around 100%.

normal rpc

This could be one of the ways to fix these types of issues on your exchange 2007 environment if you face.

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