Third Party Browsers and OWA

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David Bolton

We are just getting underway on our migration to Exchange 2010. We are primarily a Macintosh shop (except for our Windows infrastucture), so most of our users run Safari or Firefox. We conducted extensive testing on Safari and Firefox with different Macintosh Versions for over three months before committing to a pilot. After which (again several months) we committed to a full blown deployment/migration. Where we identified one javascript looping issue on Safari 3.2 a month or so ago, it was resolved by deploying Exchange SP1. We saw only that one issue in regards to using third part browsers... until recently.

We have about 100 users on the new system (1300 to go), some have been migrated from our previous IMAP mail server (not exchange), and some have been just switched over (new account on new domain, new mailbox, no messages migrated). We have designed and pretty much overbuilt our Exchange 2010 infrastructure in regards to actual user mailbox numbers and capacity (see configuration below).

For about the past month (pre SP1 patch) our users have been experiencing what they call spinning beach balls and major hangs in OWA when accessing folders or sending an email. Often resulting (impatience in wanting to get their work done) in the user killing Safari or Firefox and then re-opening it . Patching with SP1 has not resolved the issues. So far we see the issues on only some Mac clients, but with either browser. We had one Windows XP user that experienced similar issues, but a reconfiguration of the power management settings for the NIC resolved them. We thought the same was occuring on the Mac's but it happens on both Desktop and Laptop based Macintoshes.

Our Setup; All Server 08 R2 Enterprise running on:

Physical Server: Dell R510 (plenty of horsepower!) running MB, HT, and DAG, 6 TB of storage.

Virtual Server: VMWare vSphere 4.1 connected to equallogic SAN, Secondary MB and HT for DAG passive copy primarily.

Physical Blades (2), Dell PE 610's running CAS (in CAS Array) with WNLB

SAN certificate is deployed for CAS and MB servers.

Now, before anyone gets into the whole "running on a Mac" thing, Exchange 2010 was designed with consideration to support the OWA premium experience for Safari and Firefox. IIS which hosts OWA can support a ridiculous number of connections-far surpassing anything we would use. It almost seems like Safari or Firefox is losing the browser session, but if the user waits long enough, the spinning beach ball stops and the user can proceed. The IIS logs show no disconnects unless the user actually kills the browser app.

We really need some ideas here as we are stumped as to why we are experiencing these issues on only some clients. A couple of our users are seeing these issues up to five or six times a day. With another 1300 users to go, with 90% of them running on Macs, this is a real problem.

Any help would be greatly appreciated!

Thanks -David


Hello David,
Verify in Application and system logs of Exchange server and make sure that there aren't any errors or warnings about the clients. Configure Netmon and capture traffic when the issue is happening and this should give some information on where the delay is.



Jon-Alfred Smith

Basically I think you have two potential sources of error:

(1) WNLB might pose some problems. For OWA / ECP the recommended persistence methods are Cookie (either existing cookie or one created by an hardware load balancer aka LB-cookie) with a fallback to Client IP (source IP address).

(2) Being mostly a Mac shop with Exchange ... Don't get me wrong, I love my MacBook Pro, but as Apple would have put it: OWA 2010 Premium is the most advanced AJAX application on the planet. To make it work with Safari and Firefox on a Mac, there are literally hundreds of small browser specific tweaks and modifications that need to be figured out by the developers.

In the testing phase I would eliminate WNLB, either by disabling it and directing all clients to the same CAS server, or using an HLB (Kemp is a good choice with VMware). Figure out which version of which browser works best (I use Safari 5.0.2 on Snow Leopard). OS X 10.6 has some Exchange support on par with the iPhone right out of the box (might suffice for at least some of the users). And then there is Outlook 2011, which really is impressing, a huge jump from Entourage 2008.

Btw, Kemp offers a free trial for 60 days on VMware.

Load Balancing Exchange 2010 Client Access Servers using an Hardware Load Balancer Solution (Part 1)

Understanding Load Balancing in Exchange 2010
MCTS: Messaging | MCSE: S+M | Small Business Specialist

David Bolton


Thanks for the response. Bypassing the WNLB was going to be our next step however, before I even added the CAS array with WNLB, folks were seeing the timeout issues, primarily when switching between folders. Originally we began our pilot with our primary MB/HT server also hosting the CAS role, just no array. We were hoping that by adding the CAS array behind a WNLB might remedy the issues, but it has not (just added another layer of complexity to troubleshooting it ;-).

Polling over the log files has yeilded nothing (as Bharani mentioned). Running wireshark will be another course of action, just haven't done it yet. Another factor here is that we are a school district, meaning 1) we don't have the money to buy the latest and greatest, and 2) we are often several years behind in operating system upgrades (lack of funding). We have a myriad of client versions ranging from 10.4.11 to 10.6.4. We see this primarily on our 10.6.4 running Safari 5.0.2 and 10.5.8 running Safari 4.05. If you can believe it, we are still finishing up moving most of our 10.3.9 machines to 10.4 and above, just so folks can get to OWA!

Part of our decision in moving from our old mail server was to also eliminate support for the myriad number of client versions our techs were supporting, not to mention the constant Apple Mail bugs that were rearing their ugly little heads (which in some cases brought the entire mail server down for as much as three days-indexing issue on a flat file system). Going to OWA made sense especially since Microsoft touted support of the premium experience for OWA on Safari and Firefox.

I will definitely check out Kemp as it looks very promising too.

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