How to use Outlook Cached Exchange Mode on XenApp and XenDesktop

A little bit of knowledge can save you a lot of time (or even an arm).

As I mentioned previously, I’ve been building a new desk for my wife. For this particular project, I drew the entire desk to scale in a CAD program. The drawings were detailed to the point that they included the depth and width of the dados and rabbets (not the animal hopping in my yard). I wasn’t always this detailed. Years ago when I started woodworking, I would oftentimes just wing it. I would have no plans, no dimensions; only an idea in my head for what I wanted to build. I would eventually succeed, but it cost me in wasted lumber and time because I would cut a board to short as I forgot to include an extra ½ inch length for the dado. With this particular project, because I took the time to draw it out to scale, the entire build went smoothly and with no wasted lumbar.

The same thing happens in IT when we try to implement something new. We oftentimes don’t think through the solution enough to come up with a solution that will align with our circumstances. Let’s think about the discussion with Outlook and whether or not to implement Cached Exchange Mode. If we use Office 365 as our Exchange Server but still implement the native Outlook client on a XenApp server, we would most likely recommend enabling cached Exchange mode.

Mailbox size

I have some concerns with ending it there. With Office 365, every user is granted 50GB of mailbox storage. If I use Cached Exchange Mode, then I will have to accommodate 50GB of storage space for every user. This will break my storage bank. Plus, I personally find it crazy to keep a complete copy of that mailbox in two places.

Recommendation 1:

• Download the Microsoft Office Administrative Template files for Office Customization (Group policy)
• Set the Sync Settings policy to limit synchronization to 3 months.

This will limit the size of the cache file by only caching the last 3 months. Most users only access emails that were sent/received within the last 3 months. Anything older are still accessible, but via online mode only. In online mode, the access might be slower, but the frequency of users accessing those files is extremely small so why waste valuable resources keeping them local.

Storage location

My other concern is where do I store my cached file? In the blog “When to use Outlook Cached Exchange Mode on XenApp and XenDesktop?” we already said that a network share is the best option due to the non-persistent nature of XenApp and XenDesktop pooled desktops, but where?

Personally, I prefer the user’s profile directory and not their home drive. If a user sees a file in their home directory they don’t recognize, they will end up deleting it (I know I do that). I don’t want the users to physically manipulate that file. If the file is in their profile location, it becomes more difficult for the user to delete the file as they typically don’t have Explorer access to this location.

Recommendation 2:

• Decide where in the profile path to store the Cached Exchange Mode file (.OST) file.
• Use the Microsoft Office group policy template to set the Default Location for OST Files

Folder redirection

This now brings us one more question; should we leave the OST file on the network share and access it via the network or do we sync the file to the virtual desktop and access it locally? I believe that by keeping the file on the network share, we simplify the environment and put less strain on the physical servers hosting our virtual XenApp and XenDesktop machines. Plus, test data I’ve seen shows this to be a perfectly acceptable solution, especially when the file server is configured correctly with at least SMB 2 and the file server resources are monitored appropriately, which we should already be doing.

Recommendation 3:

• Utilize Citrix Profile Management
• Set a policy for Profile Management that excludes the folder containing the OST from being copied to the XenApp and XenDesktop hosts.
• Utilize at least SMB 2 on the file server and monitor appropriately

White Paper Reference: Deployment Guide: Office 365 for XenApp and XenDesktop

Blog Series Summary:

• Part 1: Is Outlook Cached Exchange Mode on XenApp and XenDesktop supported?
• Part 2: When to use Outlook Cached Exchange Mode on XenApp and XenDesktop?
• Part 3: How to use Outlook Cached Exchange Mode on XenApp and XenDesktop?