Background to PST Files
PST files are widely used in many large organizations, however not many administrators actually know how many files they have. In our experience organizations typically have between two and four PST files per active mailbox. As each might possibly contain up to 10,000 messages and attachments, and about 1GB of data, there can be a very significant volume of data to be migrated.
These files can be located almost anywhere. Often they are located on end-user systems such as PCs or laptops, or on user drives on network servers, although they are sometimes found on removable devices such as USB drives. As they are under end-user control they are effectively unmanaged and are often not backed up.
Decide your Management Strategy
First, you should decide your overall strategy for dealing with PST files.
Back into Exchange or Office 365
Microsoft recommends that all PST files are eliminated, as they are not a robust format and were never intended for long-term data storage. Data within PST files should be migrated back into your Exchange environment (either on-premises or in Office 365) where it can be managed effectively.
Of course there are good reasons why users created these PST files in the first place, and Microsoft has made enhancements to Exchange and Office 365 recently to address these concerns. The most significant improvement is the Archive Mailbox (or ‘In-Place Archive’) feature which replaces the old ‘Personal Archives’ feature in Outlook and allows end users to store and keep email in Exchange completely separate from their primary mailbox. It retains the previous user experience, and some Office 365 plans even offer unlimited storage for this feature. From an administrative perspective this brings all email back within the organization’s Exchange environment where it can be centrally managed.
To a central network location
An alternative approach is to retain PST files, but move them from end-user locations over to a central network location where they can be centrally managed and backed up. This sounds attractive as an interim solution, but it is not a good long-term approach as PST files can be easily corrupted by issues with network connectivity. It will also generate significant ongoing network traffic and likely give poor performance to end users, and it is important to note that Microsoft specifically recommends against taking this approach.
Into a central archive
Another approach is to migrate data from PST files into a third-party archiving solution such as Barracuda’s Message Archiver or Cloud Archiving Service. This can be effective if you already have such a solution already in place, or if you are considering implementing one to manage your existing Exchange environment.
Just delete them
Finally, you could simply delete all the PST files your users have. While this is probably not acceptable in all cases, we find that in many organizations a large percentage of the data stored by users in PST files is obsolete or no longer wanted. If you can identify which files need to be retained and which data within these files is still relevant, you can then delete the rest and greatly reduce the amount of data that needs to be migrated.
Identify your Migration Method
Having decided your migration strategy, you then need to decide the method for implementing this strategy.
Ask the user
You could ask your end users to identify all their PST files and migrate them individually. This approach works well in the smallest of organizations, but can rapidly become unmanageable as the number of end users increases. It is almost impossible to keep track of progress, and even the most organized of users will often get distracted onto other more important or interesting tasks.
Use free software
Microsoft provides ‘PST Capture’, which is a free tool that discovers PST files and migrates them into end user mailboxes. While it does provide a basic capability, it doesn’t scale up to the level required by medium and larger size organizations. It requires a high level of manual intervention and doesn’t cover all the tasks involved in finding, organizing, migrating and finally deleting PST files, so it is better suited for smaller organizations.
Finally, there are several very good third-party tools available, including our own PST Enterprise. These tools can manage the whole migration process for even the largest of organizations, performing many of the migration tasks automatically while minimizing the impact on your end users, and these tools can prove highly cost-effective.
Choose your Migration Solution
If you have decided to use a PST migration tool, the final task is to review the functionality provided by the various products and decide which one is best for your particular organization.
There are many different versions of Exchange, Windows and Outlook in common use across organizations, so make sure the product you choose supports your particular environment. Some products only support current platforms, whereas others will support older platforms back as far as Exchange 2003 and Outlook 2003.
A PST elimination project will typically have three distinct stages, so it is convenient to look in turn at what’s important for each of these three stages.
Stage 1 - Locate your PST Files
Most IT departments know where to look for PST files, as they are typically located on end-user devices and network drives - although they can of course be almost anywhere. The bigger problem is how to go about looking for them and deciding what to do with them.
In order to discover every PST file in your organization the product will need to do a thorough scan of each end user device as well as every network location where PST files are likely to be stored. Some products can also scan user Outlook profiles to locate any PST files that are currently open in Outlook, and using both approaches in parallel will increase the certainty of discovering all PST files. When managing your migration project it can be useful to be able to restrict the scan to specified locations or paths, particularly if you already have a clear idea where PST files are located.
You will want to minimize the inconvenience to your end users. Some products require that you install a client component on each end user machine to be scanned, while others run purely in-memory and leave no permanent footprint. A few products take a different approach and scan end user devices remotely from a dedicated server.
As each PST file is located you will need to identify an owner for it and then decide where it should be migrated to. Sometimes this is easy (for instance, it may be attached to a particular Outlook user profile), but in other cases – such as when it is on a network drive – you may need to analyze the contents of the PST file to determine the likely owner. The more advanced products will automate this process for you, as well as removing the password for any protected files if needed.
Some organizations will want to give each end user the option to decide how their own files are processed and where they are moved to, so the ability to provide end-user self-service is something you might look for in a product.
Stage 2 - Migrate your PST Files
Do you want to migrate PST data to Office 365 or to on-premises Exchange, into the Live mailbox or the Archive mailbox, or to a specified network location? Make sure that your chosen product can actually support your chosen migration strategy.
Minimize the impact on resources
There can be a very significant amount of data stored in PST files, so you will want to lessen the impact of moving this quantity of data across your network. One obvious feature to look for is a product that compresses data during transmission, and this may also include data encryption for added security. You can also reduce network traffic by chosing a product that can identify and eliminate duplicate content at source, so you are only sending a single copy of your data across the network.
Most products operate by routing or staging all data via a central server. This two-stage process can cause bottlenecks and give poor performance, so a few products take a different approach and route data directly from source to target mailbox in a ‘single hop’ avoiding any central server.
You will also want to make sure that performance of your migration is not restricted by throttling policies in Office 365 and Exchange. This is a particular problem for those products which use a small number of dedicated Admin logons to upload data to mailboxes. Those products that migrate directly from source to target mailbox will instead use the end user logon associated with each target mailbox; this parallel processing approach is much less susceptible to throttling as well as being highly scalable, and can typically give a much better overall level of performance and throughput.
Network connections can be unreliable, and end users can shut down their machine or disconnect from the network at any time, so ensure the product is fault tolerant and robust enough to cope with these situations. It should be able to resume from where it stopped should migration processing be interrupted for any reason without having to reprocess any data.
Minimize the impact on end users
End users will often structure the way they store data in PST files, either by setting up folders within each file or by setting up a number of discrete files with structured naming conventions (e.g. by date or by project). If this is important then ensure your chosen product is able to maintain or replicate this original structure when data is migrated.
It is likely that some PST files will be open within an end user’s Outlook profile, so another way to minimize the impact on end users is to choose a solution that can process PST files even if they are open in Outlook. Some products are unable to process these files, and require that the end user closes them first.
Minimize the scope of the project
The easiest way to reduce the scope of your migration project is to limit the amount of data you have to migrate. If you don’t already have one, you need to agree on an email retention policy defining how long email data needs to be retained for, then choose a product that can look inside each PST file and delete obsolete or unwanted data based on this policy. Then you will only have to migrate data that needs to be kept. There may of course be some PST files that can be deleted completely, so look for a product that also includes this functionality.
You will probably need to provision additional storage for data that has been migrated. If you have decided to retain PST files in a central location then you can reduce your additional storage requirements by choosing a product that will compact PST files after moving them. If you are moving data into an onpremises Exchange server then some products are able to uphold mailbox quotas and will not attempt to migrate a PST file if there is insufficient room in the target mailbox.
Stage 3 - Eliminate your PST Files
Finish the job
It is important to finish the migration process by tidying up afterwards, so look for a product which will delete existing PST files after migration has completed even if they are still open in Outlook. Not only will this regain storage, it will also avoid confusing the end user.
As a last step, your chosen product should change settings in each end user’s Outlook profile to prevent them from creating any new PST files.
Manage the project
A PST migration project is often complex and can run for several months, so ensure you have the features to allow you to manage the project effectively. You will need information for management level progress reporting, and it is also useful to have a full audit trail to refer to after the event.
Many products include sophisticated processing rules that allow the core of your migration operation to be fully automated. Once these products are up and running, most of your involvement will be in resolving anomalies and error situations such as corrupted PST files, as they are flagged up to you.
Administrators many want to supervise the migration operation to ensure the load on their networks does not impacting on going operations and end user productivity, so features such as processing windows and threshold settings are important.
Whichever product you choose, we strongly recommend that you install an evaluation copy of the software and run a small proof-of-concept exercise before you go ahead and make a commitment to a particular vendor. Not only will this confirm that you have made the right choice, it will also give you valuable information to help you plan your migration project.
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