I’m sure that a lot of people have seen this issue before when migrating to Exchange Online:
The BadItemLimit was exceeded and therefore the move request failed.
A while a go Ben Winzenz wrote an excellent post on the You Had Me At EHLO blog, where he mentioned that there was a change in Exchange Online and now failed mapping of SIDs will count towards the BadItemLimit.
So far so good, but how do we solve such issues when increasing of bad item limit is not an option and you have to migrate approx. 130.000 mailboxes?
When it comes to Exchange Online migration and you have a lot of SMTP namespace, you might run into issues
- when you’re trying to migrate the user
- when you try to grant Send As permissions
I spent last weeks quite some time with Outlook performance issues in an Exchange Hybrid scenario. In addition this is not a normal Hybrid as here multiple Exchange Organizations from different AD Forests without any Trust Relationships are involved.
Thus I’m not talking about the scenario described in TechNet Multi-forest hybrid deployment scenario. It looks more like this:
This post is about my personal journey with a cross-forest migration.
When it comes to account migration there is no way to do so without sIDHistory. It would be really hard to have a smooth migration without.
By using this attribute a end-user most likely won’t experience any impact…..unless you start doing a cleanup of this attribute.
In terms of Exchange users might see something like this
But what’s behind those issues and how could you mitigate this? I was part of a migration, where those issues popped up and I’m going to describe how you could determine possible impact for end-users before it happens.