Exchange Information Store Performance Issues

By Author: group wise
Total Articles: 21
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Performance of Exchange Information Store might vary when it tries checking discretionary access control list or DACL on public folders. Access Control List (ACL) entries might affect Public Folder performance on a computer which is running Exchange 2000. When an Exchange user tries to use public folders, the Exchange Information Store service examines the permissions on the public folders to determine what kind of access should be offered to the user.
The behavior occurs by reading the ACL of the public folder. Problems in resolving the entries of ACL to Active Directory service objects might result in slow responsiveness of Exchange while the Information Store needs server processing resources to complete the ACL resolution. Exchange users might complaint of long response time after selection of a public folder or general Exchange performance issues. At this time, user might receive a message prompting:
Requesting data from Microsoft Exchange Server. Outlook is retrieving data from the Microsoft Exchange Server ExchangeServerName.
The performance of Exchange slows down due to ACLs ...
... containing accounts that cannot be accurately resolve to Active Directory objects. Every account listed on ACL needs to be resolved in the Active Directory and slow performance might occur if the problem occurs during account-resolution attempts. Resolution difficulty might occur if an unknown account is encountered on ACL. The unknown accounts are at times termed “zombie” users.
Zombie users might affect the performance of an Exchange server by extending the ACL resolution process. These users can be created id Exchange 2000 Server or Exchange Server 2003 replica of public folders is not updated after the mailbox is deleted from Exchange Server 5.5 computer.
The user related to that mailbox when remains on the replicated ACL of public folder, now becomes a zombie and cannot be resolved. Therefore, every time that public folder is used, Exchange tries to resolve the accounts that are listed on the ACL. This process too results in varying (slow) performance of Exchange when zombie users are listed as the zombie user cannot be upgraded.
If ACL is available on a heavily-used public folder and there are ACL-resolution issues, Exchange process threads may start to queue, waiting to use the resource that has been locked by the resolution process. After the threads gain access, they try the same ACL upgrade that failed earlier. This may result in remote procedure call (RPC) thread pool to become used up. This also results in restriction of more clients from connecting to the Information Store. This is how Exchange Information Store performance can slowdown and affect other processes.
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