Outlook Performance issues with cached mode off

[titch]

Hi All.

 

We've had cached mode switched off via group policy for quite a while as it seemed to fix several glitches. Since doing so I have noticed that often outlook freezes for a few seconds each time it checks back online for new content which can be quite often. Our machines/network/pipe are all decent so I'm not sure what is clogging it up when calling home. Anyone got any ideas on what I could change to sort the issue?

 

Cheers

[chaplic]

You have cached mode turned off. This is what happens. I've seen it even with a dedicated 1GBit expressroute to Microsoft/ O365. Outlook 2016 is better mutli threaded but the issues remain.

 

Non cached can only be always performant if you are literally next to the exchange servers. There's no reason to not have cached mode, and even solutions for non persistent environments.

[titch]

Thanks Chaplic

 

We have always encountered more problems with cached exchange with botched profiles and "click to load from server" etc. In my opinion, I have always thought email should be live rather than cached anyway as it seems old hat to me to be pulling and pushing emails to a local machine rather than just viewing them live.

[chaplic]

That is a reasonable opinion to have, but simply does not reflect the way the product is designed to operate, especially in O365. Over the past few years I've had hand in design and implementation of 100K+ usermailboxes at various companies and apart from some specific exceptions they all run OST files relatively trouble free.

 

There is absolutely no reason, configured correctly, offline sync (OST) should cause regular issues. So I would focus my energy on solving something that should work, rather than trying to correct what is operating as designed.

[titch]

Cheers will go back and do a bit of testing. See if I can make cached mode a bit more happy

[Lucasosborne]

We were having performance issues after we first went from onsite exchange to 365, most people couldn't even load outlook without an error as it was so slow. We now have cached mode turned off and everything works about as well as onsite did! We found in DNS our proxy had 3 entries (One for it's domain IP, one for the wireless IP and one for it's heartbeat to the failover) we removed the wireless and heartbeat entries as they aren't needed by any domain computers and ran a ipconfig /flushdns on all computers Outlook started to run exactly as expected! Double check your DNS for entries to check there are no duplicate entries for your proxy as it seems to pick one at random and then time out.

[mikes]

I have had a call from our repro person complaining of slow speeds in outlook (onsite exchange), just as you described it (hanging, wheel of doom etc). This was with cached mode off - I turned cached mode off as she was having a problem with synchronization - out of memory e-mails flooding her inbox with it enabled. Everyone else uses the default cached mode with no problems, no idea why she was getting these exchange synchronization error e-mails. (her mailbox was not in the top 10)

 

I never had a problem disabling cached mode on Office 2013 and below; it seemed to function fine. Why doesn't it work properly now? If it is not meant to operate thus then why have the option? Sounds like another MS bug to me. Our DNS etc is fine

[win]

To avoid profile issues you can use cached mode for their personal email account, and online (non cached) for shared mailboxes. Normally you only run into problems when the user has multiple shared email addresses (which are less frequently used anyway)

[chaplic]

Outlook 2016 works Better in online mode than in the past as it is more multi threaded.Still not flawless. Having an on prem email server is the only sensible way to run Online mode. You are still exposed to exceptionally high number of items in a folder, and disk i/o bottlenecks on the server.

[Bruce123]

I was just following this thread, a couple of issues we encountered with caching exchange mode enabled (with o365):

 

If a user intends for an email to be sent at a specified time ("the do not send this email before" feature under options which usually means "send it at this time"), it will only send it if Outlook remains open at the time specified. So if user wanted to show off by scheduling an email to be sent at 6:00am (like hey look how early I start work), they'll be disappointed.

 

Also, if a new distribution is list is created it can take a while to show up on the Global Address Book (which will be in offline mode if caching is enabled, unless anyone knows otherwise?). Microsoft docs seem a bit vague about how often it updates, but in my experience it can take a few hours.

 

These are two issues reported to us by users, rather than theoretical disadvantages.

 

We experimented with disabling caching for 10 users, but 2 of the 10 reported occasional latency issues when scrolling through emails (as you'd expect), so the compromise seems to be enable caching but only cache 1 month.

 

We also had one other issue reported by a user with a huge mailbox (I think it was something like 50GB) and Microsoft I think advise not using caching for mailboxes above a certain size (I think it is 30GB), but that's more of an issue with the end user not deleting emails.

 

Kind Regards,

 

Bruce.