Question on OAB download during Mailbox movement.

Hi All,

I have deployed Exchange 5 2013 (3 multi role and 2 CAS )in my environment, i already have Exchange 2010 servers. All users mailbox resides on Exchange 2010 servers as of now.

I have created a new OAB for 2013 server an arbitration mailbox and assigned the new OAB on 2013 MBX DB's.

I am planning to perform a move mailbox for users starting next week in phase wise. And my question is after moving the mailbox from Exchange 2010 to 2013 will the outlook client try to perform a full OAB download for moved users mailbox.

If yes how can i plan to restrict the OAB downloading size for these users, as i don't want every user moved start the Full download of the OAB immediately and cause N/w bandwidth choke up. As my OAB size is ~790 MB and i have around 8000 Mailbox's.

Everyday i plan to move at-least 200 mail

July 17th, 2015 5:02am

When you move the mailbox only the URL's are updated reflecting the new server details, so in outlook you wont have to create a new profile, but OAB will be downloaded because when the OAB Urls changes the outlook will download the new OAB from the server. However it depends on how many users u migrate concurrently

You cannot restrict the OAB download as in 2013 oab generation and distribution are changed

http://blogs.technet.com/b/exchange/archive/2012/10/26/oab-in-exchange-server-2013.aspx

Free Windows Admin Tool Kit Click here and download it now
July 17th, 2015 6:38am

Thanks for the reply, i need something which can help me in the same.

Just came across below article

http://blogs.technet.com/b/appssrv/archive/2012/02/20/branchcache-for-exchange-2010-oab-download-how-to.aspx

Not sure how much this can help

July 17th, 2015 8:12am

that's for 2010, 2013 oab generation and distributions are different
Free Windows Admin Tool Kit Click here and download it now
July 17th, 2015 11:18am

I would not worry about network bandwidth used by OAB downloading. Migration of 8000 mailboxes easily takes a few weeks or even a few months. And OAB downloading is based on BITS. Not likely it will cause any bandwidth issue.

But 790MB OAB for 8000 mailbox looks very much too large. I would investigate what went wrong.

July 17th, 2015 11:44am

Hi Li,

Yeah that's my worry 780 MB is huge size and my servers are centrally located in a DC and users spread across 7 different location, hence wondering how can i achieve this task on OAB part.

Free Windows Admin Tool Kit Click here and download it now
July 20th, 2015 1:32am

If you give Exchange Server Deployment Assistant a spin and enter the data for your scenario (migration from Exchange Server 2010) you'll actually see that in the detailed step-by-step output you'll have a separate step for OAB - named "Configure Default Offline Address Book" - and also the detailed required cmdlets to run in order to not hit the problem you mentioned. This is mentioned as well in the Technet checklist for migrating from Exchange Server 2010 to 2013.

You're actually looking to assign an Exchange 2010 OAB to all the databases that don't have a fixed OAB specified:

Get-MailboxDatabase | Set-MailboxDatabase -OfflineAddressBook "Default Offline Address Book"

But again - go through the Exchange Server Deployment Assistant to see the exact order of operations and various gotchas along the way.

As for the large OAB - to my understanding this is the one located on the new Exchange Server 2013. You could try creating a new one (without assigning it) and verify the resultant size for comparison. Steps are detailed here.

July 20th, 2015 2:43am

I don't think you get my point :)

What I meant are,

1. 790MB OAB for a 8000 mailbox system indicates something went wrong with your OAB generation. You should fix it.

2. Event though OAB is large, I don't think it will cause network congestion.

Free Windows Admin Tool Kit Click here and download it now
July 21st, 2015 1:56am

I got your point :)

780 MB is for Global Exchange org OAB size, i am just part of one region where i have 8000 mailbox's.

Global count is more than 500,000 Mailbox's + EDL's + Contacts.

Hence i don't think there is any issue with my OAB.

July 21st, 2015 3:07am

In this case I would suggest not to use the default GAL. It's not efficient to have 500K to 1M entries in GAL. Logically every sub division should have a unique GAL while there is another AB (not downloaded to Outlook) contains everyone in the organization.
Free Windows Admin Tool Kit Click here and download it now
July 21st, 2015 3:38am



I was trying to check this artcile which says you can try to perform a manual offline address book deploy.

https://technet.microsoft.com/en-us/library/ff969354(v=office.14).aspx

i tried as mentioned in the article and noticed that there are .tmp extension files created when outlook says OAB is downloading and then it disappers leaving the orginal files which i had copied from other machine updated in size.

Does anyone have any idea about this. If this is works normally i will use my SCCM to push the OAB file and registry to all users machine and then start moving the mailbox's.

July 28th, 2015 7:28am

Anyone who has checked this?? Anyone came across this scenario??
Free Windows Admin Tool Kit Click here and download it now
August 12th, 2015 3:02am

This topic is archived. No further replies will be accepted.

Other recent topics Other recent topics