Hi, We have Exchange 2007 setup with Single copy Clustered Mailbox Server. We were facing Disk I/O issue earlier where Disk read/write was crossing 80ms and post that we have chnaged the storage to mitigate the Disk I/O. Now the Disk I/O issue is resolved but started observing high CPU utilization in Mailbox Server and shoots to almost 100% during peak hrs. This causes in Mail queue and delay in mail flow. Mailbox Servers are having 8 GB RAM and 2 dual core Processor. We also have 2 Hub Transport Servers. Exchange Servers are running with Exchange 2007 SP2,rollup1. Kindly let us know if any known issues to fix the high CPU utlization of Mailbox Servers. Regards Mahesh

Hi, First I recommend you to apply the latest update for your Exchange Server. Please try to run ExBPA to have a health scan and then check the result. I recommend you to use Process Explorer to check what eat CPU. You can download and extract Process Explorer from http://www.microsoft.com/technet/sysinternals/ProcessesAndThreads/ProcessExplorer.mspx Please check the article below, the memory that we recommend is to have 2gb+2~5mb/Mailbox. If you have other roles install together with the mailbox role, then more memory should be involved. User Type Mailbox Memory Recommendation Light 2GB + 2MB/Mailbox Average 2GB + 3 ½MB/Mailbox Heavy 2GB + 5MB/Mailbox UPDATE 2: Exchange 2007 Processor and Memory Recommendations http://blogs.technet.com/b/exchange/archive/2007/01/16/3397755.aspx How to troubleshoot Store.exe process uses almost 100 percent of CPU resources? http://social.technet.microsoft.com/Forums/en-US/exchangesvrgeneral/thread/d46bf491-0e5b-4b9e-81b3-81c66b6ad81c#20 Xiu Zhang Forum Support Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

Hi, First I recommend you to apply the latest update for your Exchange Server. Please try to run ExBPA to have a health scan and then check the result. I recommend you to use Process Explorer to check what eat CPU. You can download and extract Process Explorer from http://www.microsoft.com/technet/sysinternals/ProcessesAndThreads/ProcessExplorer.mspx Please check the article below, the memory that we recommend is to have 2gb+2~5mb/Mailbox. If you have other roles install together with the mailbox role, then more memory should be involved. User Type Mailbox Memory Recommendation Light 2GB + 2MB/Mailbox Average 2GB + 3 ½MB/Mailbox Heavy 2GB + 5MB/Mailbox UPDATE 2: Exchange 2007 Processor and Memory Recommendations http://blogs.technet.com/b/exchange/archive/2007/01/16/3397755.aspx How to troubleshoot Store.exe process uses almost 100 percent of CPU resources? http://social.technet.microsoft.com/Forums/en-US/exchangesvrgeneral/thread/d46bf491-0e5b-4b9e-81b3-81c66b6ad81c#20 Xiu Zhang Forum Support Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.