Evaluate Weigh the pros and cons of technologies, products and projects you are considering.

New Outlook 2013 features help manage OST files

Managing the size of users' OST files is greatly simplified in Outlook 2013 with the arrival of two new features.

In past versions of Microsoft Outlook, administrators often had to make certain compromises when it came to managing...

OST file bloat. In Outlook 2013, Microsoft has introduced two new mechanisms that help balance these files dynamically and intelligently.

As the workforce has grown increasingly mobile, Outlook Cached mode has proved its worth. Road warriors can enjoy the full contents of their mailboxes even over high-latency links, knowing that Outlook is synchronizing outbound messages and incoming updates in the background as network conditions allow, permitting content lookups and searches from a local OST file.

The mobility trend, however, has run squarely into opposition with another trend: large mailbox sizes. At some point, the amount of data in a mailbox creates an OST file that is unwieldy for one of these reasons:

  • The file is too large to fit into the limited storage on mobile devices.
  • The file is too large for slow mobile disks to search effectively.
  • The sync rate from the large mailbox is too much for network conditions.

In previous versions of Outlook, administrators would do things like add expensive, large solid-state drives to mobile devices, or keep user mailboxes small in order to combat these problems. In Outlook 2013, admins now have two new tools at their disposal: Sync Slider and Exchange Fast Access.

The Outlook 2013 Sync Slider

In previous versions of Outlook, a profile using Cached mode (enabled by default on new profiles) pulls down all the data in the associated mailbox. Most users, however, most frequently access their recent data. The older a message item is, the less likely the average user needs to refer to it.

Based on those metrics, Microsoft has included the new Sync Slider in Outlook 2013. The tool lets administrators change the upper age limit of the data it synchronizes.

Outlook 2013 Sync Slider
Figure 1: The Outlook 2013 Sync Slider is set to 12 months by default.

Whether you upgrade an existing profile to Outlook 2013 or create a brand-new profile, the slider is set to 12 months by default. You either can set it to one, three, six, 12, or 24 months, or permit Outlook to continue syncing all items as previous versions do. Items older than the sync limit will not be pulled down into the OST. Administrators can also use the "Cached Exchange Mode Sync Settings" setting in a Group Policy Object to control the Sync Slider across their organization.

For existing profiles, Outlook 2013 doesn't use the existing OST file. Instead, it converts the file to a new format that provides additional compression. Between the improved compression and sync limit, the resulting Outlook 2013 OST files will be significantly smaller and offer a great balance between space, convenience and performance on mobile devices with limited storage.

Exchange Fast Access in Outlook 2013

The flip side to partial synchronization is that there are times when you need to pull up data not in your local cache. Online mode is the traditional answer, but that requires a constant connection with low latency and sufficient bandwidth to provide a good user experience.

With Exchange Fast Access, the Outlook 2013 Cached mode dynamically contacts the server to pull down the missing information as if it were in Online mode, all without switching out of Cached mode. Searches that result in hits outside the cached data display a prompt that the user can click to pull down additional results.

Check out some of the most important new features in Exchange 2013

This feature helps improve Outlook 2013's startup response time. When it starts up, Outlook simultaneously pulls down new items in Online mode, even as it begins the normal Cached mode sync process. Users immediately see new items and begin searching, reading and sending messages while the OST file is brought quietly and efficiently up to date in the background.

As with the Sync Slider, administrators can control the behavior of the Exchange Fast Access feature in their users' Outlook 2013 profiles via Group Policy Objects. The "Disable Exchange Fast Access" setting is a simple switch: Enabling the policy element disables Exchange Fast Access, and you revert back to legacy behavior.

Putting it all together

Before you upgrade to Outlook 2013, think carefully about what your users need. Consider mailbox size, the types of mobile devices your company allows (and the storage available), and your users' particular access patterns. Doing so helps you determine the correct set of policy settings for your organization. You can read more about these settings in Microsoft's TechNet documentation on Outlook 2013.

Understand that these settings and behaviors don't apply to protocols other than Outlook Anywhere. Protocols like Exchange ActiveSync -- which already has a time-based sync setting -- are not affected. This means that neither mobile phones nor Windows RT devices will be affected (as of the time of this writing).

Remember, deploying these tools with default settings might come as a nasty surprise for your users, especially when they realize they don't have offline access to messages older than a year, and when search results and folder browsing require extra steps.

About the author
Devin Ganger is a messaging architect and technical writer with more than 15 years' experience in administering messaging systems and Windows, Unix and TCP/IP networks. Today, he works primarily with Exchange Server, Windows Active Directory, and related Microsoft and third-party technologies. Ganger was recognized as a Microsoft MVP for Exchange Server from 2007 to 2011.

Dig Deeper on Outlook management

Start the conversation

Send me notifications when other members comment.

Please create a username to comment.