Exchange hotfix for kernel memory exhaustion issues is now released



A few weeks ago, we released three CXP flashes on the subject of Windows 2003 kernel memory issues and Exchange 2003. This is a promised follow-up to those flashes.


We are happy to announce that a new Exchange 2003 SP2 hotfix has been released that reduces the amount of kernel memory Exchange needs to support client access tokens. In internal testing, this hotfix has reduced token memory usage by up to a third. The experience of external customers has been similar.


Also, a new Knowledge Base article is now available with detailed information about managing client token memory on an Exchange server.



Memory used by client tokens is an important factor in Exchange server scalability. Client tokens are allocated from kernel paged pool memory. There is a finite amount of this memory available, and when this pool is used up, no more connections can be supported on an Exchange server. Reducing token allocations by 30% can translate directly into being able to support 30% more clients.


There are two ways to reduce the amount of memory used for client tokens: (1) reduce the size of each client token, and (2) reduce the number of client tokens on the server.


Knowledge Base article 912376 explains the token issues in detail, and includes scripts to help administrators determine how large individual tokens are. It also has suggestions for reducing typical token size. You can read this article here:


How to monitor and troubleshoot the use of paged pool memory in Exchange Server 2003 or in Exchange 2000 Server


Exchange hotfix 912480 works by optimizing internal Information Store processing to reduce the number of token copies per client. You can read more about this hotfix here:


An Exchange Server 2003 server that hosts many Outlook client sessions may run out of paged pool memory

You should install this fix only if you've already optimized token usage in your environment according to the suggestions in the Knowledge Base article, and you still are unable to reclaim as much memory as you need.
The hotfix does not get rid of token memory usage problems altogether. (Only moving to a 64-bit platform will really solve this problem.) But, as we committed to you before, we will continue to do everything we can to help you manage kernel memory limitations that impact Exchange scalability on the 32-bit platform. This hotfix and Knowledge Base article are our first deliveries on that promise.


If you are interested in the full background on this issue, please read the previous flashes on the Exchange team blog.
The first flash provided technical background about the demands Exchange makes on kernel resources.
The second flash discussed hardware configurations that can restrict the kernel memory available for applications.
The third flash summarized the effect of large user security tokens on Exchange's kernel memory usage. 

Thank you very much for your interest and for the helpful suggestions you've sent us.


- The Exchange CXP Solutions Team

Comments (7)
  1. Anonymous says:

    There is a hotfix released that will reduce the amount of kernel paged pool RAM used, typically by 1/3rd. I’m guessing they changed the internal structure of the client access tokens so that they only use 2 pages (8k on ia32) instead of 3 pages (12k on

  2. mohiuddinminhas says:

    We have to migrate from GroupWise 6.5 to Exchange Server 2003, and as per Microsoft, this migration is now supported with Exchange 2003 SP2. For example,

    we r running an e-Directory and GroupWise 6.5 on Microsoft Windows Server 2000. There is a lot of information available online for older GroupWise versions like 5.x, but specifically not enough for GroupWise 6.5.

    Any Help will be greatly appreciated

    Thx! in Advance


  3. Tim H says:

    Will this hotfix be back-ported to Exchange 2000?

  4. Mike Lee says:

    Tim asked: Will this hotfix be back-ported to Exchange 2000?

    No, I’m sorry to say that there are no plans for this. Exchange 2000 is past its extended support lifecycle. The only fixes from now on for Exchange 2000 will be if security issues are discovered.

    You do raise an interesting point: while this problem has existed for a minority of Exchange 2000 customers, most of them haven’t had kernel memory issues. Why are people suddenly running into this after upgrading?

    The reason is that a flood of new features, hardware and clients have come along in the last couple of years. Multiple upgrades tend to happen all at once: new drivers, more memory, bigger disks, more users, additional client applications…all of it adds up to more memory pressure.

  5. Anonymous says:

    Sorry for the delay… 

    Hands on with Hosted Exchange

    Step-by-Step Guide: How to repair Exchange-related…

  6. Anonymous says:

    Snapping a Database in Exchange 2003 (Brick Level Backups)

    VSS is a set of COM APIs that implements…

  7. Anonymous says:

    One of the reasons to move to 64Bit in Exchange 12 is for more memory space. We are reaching a limit…

Comments are closed.

Skip to main content