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A look at Exchange 2010’s native-archiving limitations

Exchange Server 2010 includes new built-in archiving features, but limitations with deduplication, archive message search and retrieval can cause problems for admins and end users.

Exchange Server 2010 includes broader support for message archiving than previous versions. But the built-in archival features have a number of limitations that may leave you with no choice but to buy third-party tools.

Here’s a look at the hindrances with Microsoft’s built-in Exchange 2010 archive system, including search restrictions, problems extracting and accessing archived messages and deduplication.

Deduplication in Exchange 2010 SP1
Deduplication was not part of the Exchange 2010 RTM release, but is included in Service Pack 1. Message archives are stored in an archive database, which uses the same database format as the mailbox database.

In previous versions of Exchange, deduplication was implemented at the database level through single instance storage. Microsoft did away with single instance storage in Exchange 2010, eliminating native deduplication within the mailbox and archive databases.

In Exchange 2010, Microsoft only provides deduplication in the multi-mailbox search. When performing e-discovery searches, it’s possible to enable deduplication to ensure that only one copy of each message is included in search results. However, the search-result estimate does not take deduplication into account.

In contrast, many third-party message archive solutions store your archives in a proprietary database. That database uses native deduplication to reduce storage requirements. Certain products also support both message deduplication and attachment deduplication, while Exchange 2010 does not.

Long-term access to archived messages in Exchange 2010
Exchange 2010 differs from many third-party message archiving products in how it provides archived message access. In Exchange 2010, users have a personal archive that acts as a secondary mailbox. Users can either manually place items in the archive or admins can implement rules that automatically move messages there after a specified period of time.

From a user’s perspective, the archive mailbox is a pain because Exchange admins typically implement quotas to prevent the mailboxes from growing too large. Administrators can also impose retention policies to prevent messages from being stored in archive mailboxes for a set amount of time. That means end users can’t store important messages indefinitely.

But from an admin’s perspective, quotas and retention policies are necessary to prevent the server from running out of storage space. Part of the storage problem is redundant messages stored in personal archives.

Many companies use journaling to archive a copy of every message sent or received by users. This causes a copy of every message that exists in the user’s personal archives to also exist in the journal mailbox.

Certain third-party message archiving products use a single repository for archived messages to work around this problem. I know of one product that uses retention policies to silently move messages to the archives. This process is almost completely transparent to the end user.

The user can still access archived mail through Outlook and the messages’ location appears to remain unchanged. However, once a message is moved to the archives, the message becomes read-only. This way, the user can still access older mail and the company satisfies compliance requirements by having messages locked away in a tamper-proof archive.

Message extraction drawbacks
When performing e-discovery in Exchange 2010, search results are compiled in a dedicated discovery mailbox. If you need to compile search results, they can be exported to a .pst file.

Although .pst files may be sufficient in many cases, third-party message archiving solutions typically offer more options. For example, certain third-party solutions can export messages into an encrypted and digitally signed file. This ensures that archives are not tampered with or accidentally leaked.

Searching within attachment restrictions
While Exchange 2010 does allow for searching within attachments, only Microsoft Office documents and .pdf files are supported. Exchange 2010 is extensible however and you can add search capabilities for additional file types by installing iFilters for the file types you want to support. The problem is that iFilters can be difficult to come by.

In contrast, third-party archiving tools typically offer broader support when searching for attachments. For example, certain third-party archiving tools support searching within large .zip files.

Brien Posey is an eight-time Microsoft MVP with two decades of IT experience. Before becoming a freelance technical writer, Brien worked as a CIO for a national chain of hospitals and healthcare facilities. He has also served as a network administrator for some of the nation’s largest insurance companies and for the Department of Defense at Fort Knox.


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