WilkyIT goes into detail on the topic of allowing concurrent access to the Office365 Container using VHD Difference disks to achieve this frequent requirement, especially in Citrix environments.
Below is an excerpt:
What is a difference disk?
A differencing disk is a virtual hard disk (VHD) that stores changes made to another VHD. The purpose of differencing disks is to make it possible to maintain information about changes made so that they can be reversed or merged into parent VHD if necessary.
What is the Default Access mode?
The default configuration out of the box for FSLogix is normal direct access where is the a one to one relationship with User & VHD. Only one connection can be made to the VHD at any one time therefore it would be unsuitable for circumstances where multiple session could be established by one User. No difference disk is used in this method.
Default scenario is direct access stored on the network , below an overview:-
How can i allow multiple sessions for one user (i.e Citrix XenApp)?
There is three possible options to allow multiple sessions, they are as follows
This scenario difference disk will be used and stored on the network , below an overview:-
During login if it detect for presence of difference disk on the VHD Location Share, it will successfully open and merge to parent disk and then remove the difference disk as well as any other difference disk on the users share. It will then create a difference disk in the format of %computername%_ODFC.VHD(X) and then mount that disk next to the Parent VHD on the share.
CLICK HERE to check out the full article and in-depth look at Concurrent Office 365 Container Access.