Hi all, Recently, some users complaint about slowness with their outlook. Most users get outlook 2007 now. every one uses online mode. We use Exchange 2003 server and no attachment size limit and mail box size limit. I used EXBPA and did not see any critical alerts. If I look at the server and it's fine, where should I trouble shoot this? Thank you.

You could download process explorer at http://technet.microsoft.com/en-us/sysinternals/bb896653. It would show you what's taking up so much resources at the Exchange level. If you do not see anything, it might be the client.

Some performance monitoring on the Exchange 2003 will also be useful to see. http://technet.microsoft.com/en-us/library/aa996023(EXCHG.65).aspxMVP Exchange Server

Most complaints come from users with large size mailboxes (over 5 GB) and some users with over 100,000 items and some users are with over 50,000 for inbox folder. Will this make them slow to open outlook? If yes, will cache mode help these users ? Thank you.

If you have mailboxes that have 50,000 items in the inbox, then you have exceeded Exchange 2003's recommended specs: http://msexchangeteam.com/archive/2005/03/14/395229.aspx It's item count, not size, that matters

if they create sub-folders under Inbox, will performance be better? (unfortunately, users will not clean their mailboxes plus we cannot have a limt policy) Will cache mode help these users? Another questions, for these users with lots of items over 100,000, when they open outlook, will it affec the server performance or other users? Thank you.

With Exchange 2003, you are going to see performance issues with large mailboxes regardless. You can do things to mitigate that by having users move items to the non-critical folders, but that is not a very good long term solution. Cache Mode means .ost files and as the .ost files get larger, client performance will suffer as well. And yes, the server could experience performance issues that could affect other users. Exchan ge2007 and especially Exchange 2010 are better architected for large mailboxes. I would recommend you consider upgrading if your mgmt will not use some sanity and dictate mailbox size limits and archiving.

>Cache Mode means .ost files and as the .ost files get larger, client performance will suffer as well. at which size of ost will affect client performance? 2GB? Thank you.

>Cache Mode means .ost files and as the .ost files get larger, client performance will suffer as well. at which size of ost will affect client performance? 2GB? Thank you. There is no "hard value" on when performance will suffer after ost reaches certain size. 2GB was a "recommended" value back in the days, but given your pc has good hardware specs and updated on all your Outlook 2007 patches it can go much above 2GB. OST Sizing Guidance Changes http://msexchangeteam.com/archive/2009/03/24/450881.aspxJames Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com

>Cache Mode means .ost files and as the .ost files get larger, client performance will suffer as well. at which size of ost will affect client performance? 2GB? Thank you. There is no "hard value" on when performance will suffer after ost reaches certain size. 2GB was a "recommended" value back in the days, but given your pc has good hardware specs and updated on all your Outlook 2007 patches it can go much above 2GB. OST Sizing Guidance Changes http://msexchangeteam.com/archive/2009/03/24/450881.aspx James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com It wasnt a recommendation as much as a hard limit since the ansi .ost couldnt grow much beyond 1.8 GB.

>Cache Mode means .ost files and as the .ost files get larger, client performance will suffer as well. at which size of ost will affect client performance? 2GB? Thank you. I think you'll find that large .osts will introduce / surface client performance issues. But its really a trade-off in some ways. Online Mode: MOre work for the server. Cache Mode: More work for the client. Regardless, Exchange 2003 isnt the right platform for very large mailboxes with high folder item counts.

On Sat, 12 Feb 2011 20:12:17 +0000, AndyD_ wrote: [ snip ] >It wasnt a recommendation as much as a hard limit since the ansi .ost couldnt grow much beyond 1.8 GB. Still, with 5400RPM disks and a small amount of memory most clients start to stress out pretty quickly with big mailboxes. Most desktops/laptops aren't equipped to manage a database, which is what that OST (and PSTs, too) really is. --- Rich Matheisen MCSE+I, Exchange MVP --- Rich Matheisen MCSE+I, Exchange MVP

On Sat, 12 Feb 2011 20:12:17 +0000, AndyD_ wrote: [ snip ] >It wasnt a recommendation as much as a hard limit since the ansi .ost couldnt grow much beyond 1.8 GB. Still, with 5400RPM disks and a small amount of memory most clients start to stress out pretty quickly with big mailboxes. Most desktops/laptops aren't equipped to manage a database, which is what that OST (and PSTs, too) really is. --- Rich Matheisen MCSE+I, Exchange MVP --- Rich Matheisen MCSE+I, Exchange MVP Aye. IIRC, in the early days, the cache was called the Local Information Store!

is it better to switch users with losts of item counts to cache mode since they only affect users' performance on local computers? Also, on the online mode, it will take a while to change sort order? Thank you.

Hi, I think set their clients up to use cached mode will be better than before, this will shift the bulk of reading activity to her local OST. But I would like to suggest you upgrade your environment to Exchange 2010, as Andy mentioned, the Exchange 2010 is better architected for large mailboxes. And here is an KB article to give your user: Outlook users experience poor performance when they work with a folder that contains many items on a server that is running Exchange server: http://support.microsoft.com/kb/905803/en-us Best regards, Serena Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

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