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If you're reading this paper, you probably already realize that the Personal Storage Files (PSTs) scattered around your network contain messages and attachments which should really be part of your central information store. As the need to retain corporate data has increased to meet regulatory requirements - and best practice may dictate email meeting certain internal policies - the very existence of PSTs is putting email more and more ?at risk.' So what can you do about PSTs?
This white paper outlines some ideas, methods and applications for living with legacy PST files and avoiding the creation of new ones. It will help you:
1) Assess the true facts about PSTs.
2) Help you if you have PSTs.
3) Help you to avoid the need for PSTs in the future.
Assessing the Facts
PST files are created by users as a secondary data store to save emails that they wish to retain and refer to later. But why is this necessary when they have access to mailboxes especially designed for this purpose?
The usual answer is "quotas." If mailboxes are restricted by size quotas, and users receive a notification that they're reaching the limit, they have a decision to make. Choosing to ignore the alert just provides a short-term breather. The user will soon be unable to send emails, and finally unable to receive emails.
The user reaction to hitting mailbox quotas can be alarming. This chart, courtesy of Osterman Research, shows how they cope.
If users have to delete email, but they need to retain information to do their job, they will spend longer and longer trying to find emails that can be deleted without impacting their work life. This time costs money. If this takes, for example, just 30 minutes per week, it amounts to thousands of dollars of lost productivity per employee per year. What's more, the user is likely to continue to come up against quotas and have to go through this process regularly.
This individual and selective approach also carries the risk that they will delete email critical to their work, or contrary to data retention policy.
The common short-term solution, often advised by Exchange administrators, is to create a PST file. End of story? Unfortunately, the practical limitations of PSTs are now well known and cannot be ignored, making them a less-than-strategic fix.
PSTs are not reliable places to store company information because they:
- Are hard for the administrator to locate.
- Have known tendencies to corrupt when they near their maximum size
(2GB for Outlook XP and earlier editions).
- Are not part of the normal security backup and maintenance processes.
- Cannot be easily monitored for content according to policy.
- Are inefficient in their use of disk space particularly in comparison to
Exchange mailboxes.
- Can only be accessed by a single user at a time, i.e., not available for teamwork.
- Take time to repair when damaged.
- Fill up local drives and server space.
- Removes the ability for PC independence.
Who Needs Quotas?
So, if the driving force for the creation of PST files is mailbox quotas set by administrators, but PSTs are a bad idea, why are quotas set?
In simple terms, mailboxes have quotas set to ensure there is sufficient space on the Exchange server to hold all the user mailboxes. Other factors such as keeping backup and restore times within SLAs and processing requirements of servers also come into play, but disk space is the major bottleneck.
Email Lifecycle Management
So to reduce the need for mailbox sizes quotas, we need to:
- minimize the total amount of data needed to be held in the Exchange server mailboxes and
- manage the information for longer term storage and easy retrieval.
This combined process is referred to as mailbox size management, encompassing automated email compression to reduce message size, combined with rules-based archiving to move data to more appropriate storage.
Message Size Reduction - A Continuous Process
The immediate benefit of data compression is to reduce the physical space needed to store a particular message and attachment. The improvements are typically dramatic, reducing space requirements by 50% or more.
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