Hi all,
I am trying to get some more insight related to following problem.
Our organisation decided to migrate from Online Exchange to on-premise server. As Microsoft doesn't have any option to migrate back from cloud to physical mailboxes, I went via simple route of just exporting all 22 user mailboxes data into separate .PST files.
After Exchange 2013 was deployed and tested in-house and MX record was re-pointed to on-premise server, I went via deleting all current profiles and .ost data files and re-creating profiles with new server details and importing data back to user mailboxes. There was no any obvious problem with that, until users Outlook clients started to sync with new Exchange server and push data to Exchange database and populate mailboxes with imports from these .pst.
The problem is still current - speed of synchronising back to Exchange is extremely slow - over last 24 hours, only 18 GB out of 70 for all 22 user mailboxes synced back to the server. I keep monitoring mailbox sizes via Recipients pane on ECP - sometimes it just stops. There is no way to see progress on user clients - in most cases it shows percentage and that's all. But even after it says "All folders has been updated", another Send/Receive starts synchronisation again. In order to eliminate bandwidth problem (which shouldn't be an issue at all), I reduced sync to 3-4 clients only, but it still doesn't help. One of the large mailbox users (9GB) has only 5GB synced over last 24 hours. And as I already mentioned, sync stops and resumes randomly. Most popular status messages for sync process - "Synchronising Hierarchy", "Synchronising local changes of Inbox folder" etc.
Some small mailbox users with 100-200MB mailboxes are ok, but I still have 3 users with 10-15Gb mailboxes and as this sync process disables receiving and sending of email until it's complete, I don't want to leave users without email for 2-3 days (or train how to use OWA).
I found information about recommendation to disable Cached Mode, but it didn't made any difference.
Please help with any advise, can this issue be related to Outlook client version or settings of Exchange Server? Most clients are 2007/2010.