In September 2012, I speculated whether the change in OST format in Outlook 2013 and the introduction of the “slider” would have any effect on users. As it happens, the slider – which allows users to decide how much of their mailbox should be cached in the OST for offline access – might have a more long-term effect on Exchange.
When introduced in Exchange 2010, Microsoft positioned archive mailboxes as the repository for information that did not need to be accessed on a frequent basis. The logic is that users should be able to decide on the items that they need to have access to all the time, even during network outages, and keep that data in their primary mailbox. Anything else goes in the archive, which is not synchronized by Outlook into its OST.
Assuming that users will follow any logical form of reasoning when it comes to the management of their mailbox is often a fool’s errand. The advent of dependable and fast search facilities in both client and server has let people leave Inboxes become cluttered and full with little of the old-time movement going on to move items into a well-organized filing structure.
Life being what it is, Exchange 2010 and 2013 provide retention policies and tags to allow administrators to “help” users. And indeed, if you enable an archive for a mailbox, Exchange immediately applies the default MRM (Messaging Records Management) policy to that mailbox. This has the side-effect of forcing the Mailbox Folder Assistant (MFA) to move any items over two years old into the archive the next time that MFA processes the mailbox, something that can come as a shock to an unwary user!
Archive mailboxes are part of a more general effort to use server-based stores as the repository for user data and move away from the horrors of PSTs. I don’t like PSTs very much as they are an insecure and unsatisfactory file format. However, PSTs have provided users with additional storage for many years and are very popular, even (or maybe because) they render their contents invisible for compliance purposes. Microsoft’s compliance strategy favors replacing PSTs with mailbox storage, which is the reason why Microsoft has invested in the provision of the free PST Capture tool. Other PST ingestion utilities exist on the market such as TransVault Migrator, Sherpa Software’s Attender, and Dell's Migration Manager for Exchange.
But given that the Exchange 2013 Store has its sights firmly fixed on mega-mailboxes and that Exchange Online is positively encouraging people to become human packrats by filling its 50GB mailboxes, the question has to be asked whether archive mailboxes are needed?
It is easier for users when everything is stored in one place. Those who doubt this statement simply have to observe how people look for information. Even though Outlook allows users to search “All mailboxes” in one operation, the default is to search the primary mailbox first, which is what people do. It’s logical because this is a local search and doesn’t involve asking the server for anything.
Yet keeping everything together in the primary mailbox creates a big technical problem. Laptop disks are slow and the OST file format is not the most efficient that ever left the desk of a software developer. Even with fast SSDs, Outlook’s performance tends to sag after the file size passes 10-12 GB or so. Your mileage might vary depending on the speed of your PC, the disk, other work going on, wind direction, and the day of the week. Thus, having a 50GB or 100GB mailbox is all very well, but if you fill the mailbox you create a problem for Outlook.
Enter Outlook 2013's nifty slider. Even with a huge mailbox, it’s likely that setting the slider to tell Outlook to only synchronize the last 12 months will keep the OST to a manageable and speedy size. Everything remains in the single mailbox, the user controls how much data is available offline, and we have a simplified environment to manage because no archive mailboxes are used.
You can still use archive mailboxes if you want. Perhaps you can come up with good business reasons to do so, such as the need to clearly segregate information required for a particular purpose, such as audits. And if you’re still using Outlook 2007 or Outlook 2010 you can’t use the slider control because it doesn’t exist in those clients. But the choice between all-in mailbox storage or a division across primary and archive mailboxes exists if you use Exchange 2013 or Exchange Online with Outlook 2013. It’s nice to have that choice and it’s surprising how a client-side feature sometimes has an unexpected impact.
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