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Why you shouldn't use PST files

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They have been around for years and for thousands of Microsoft Outlook users and email administrators out there, they'd be lost without them: Personal Storage Table (PST) files. If you've worked with Outlook for very long, the name will immediately ring a bell; if you've ever administered Outlook, you may already know about the problems associated with this notorious file format.

In any corporate environment - or, for that matter, any environment with an Exchange Server - the use of PST files as a permanent solution to an email administrator's problems should be banned. Let's find out why.

Problem 1: File Sizes and Data Security

The number one issue with the PST format prior to Outlook 2003 was that it was ANSI (American National Standards Institute)-based. The ANSI PST format has a maximum size limit of 2GB, and other limitations exist with regard to the number of items which can be stored per folder. However, there was a particularly problematic bug which allowed data to be written to ANSI PSTs past the 2GB limit without warning. This would result in data loss, at least past the 2GB limit, but potentially loss of all the data stored in the file.

To address these concerns, Outlook 2003 and higher introduces a new PST format which runs on Unicode instead. This format stores up to 20GB of data, but it should be noted that upgrading Outlook does not automatically upgrade any PST file(s). This must be completed manually, by creating a new Unicode file and transferring the data across.

Despite the improvements made, PST files are still susceptible to corruption issues - which will result in lost data. These become particularly prevalent as files become larger or you increase the volume of data which moves through the file. For most users, the prospect of losing precious or business-critical emails, reminders, tasks and contacts could be cause for significant concern. It shouldn't come as a surprise that you should make a regular backup of your PST file(s), but this is not completely safe, as a PST can go for weeks or months in a partially corrupted state before you realise you have a problem.

Problem 2: Network Access and Backups

PST files must be stored on a local hard disk. Accessing them over a network is not supported by Microsoft, and has not been since Exchange 4.0. Instabilities in the network, loss of network connectivity, speed issues in reading and writing from the file server can all cause issues. Furthermore, the mechanisms Outlook uses to read and write data in the PST file are not efficient when operated over a network; the commands used are optimised for handling as system calls to the local operating system. Passing these commands over the network interface is not efficient for the file server, and will cause the performance of that server to seriously deteriorate.

This has three implications for system administration:
 
Firstly, backups are already difficult to maintain, due to the issues with corruption going undetected, but will become ever more difficult to implement. As the PST cannot be run from the network, you must configure backups on each machine individually - and must ensure the backup does not run while Outlook is running. Backing up the Exchange Server is rather pointless, as the data is offloaded into the PST when the user downloads their email or hits the "Archive" button.
Second, your cost of administration increases significantly. Considering a typical organisation, which may have remote workers and several sites across different areas of the country or perhaps throughout the world, moving administration away from the server and towards the client lessens the design principles surrounding central administration, requiring more admin time to perform repetitive tasks on PST files. The system may quickly grow beyond your control, becoming exponentially difficult to track and maintain.
Your network performance will suffer. As previously noted, the commands used by Outlook are not efficient file-handling mechanisms when passed over a network interface. File Servers storing PST files for many users have been known to grind to a halt when handling multiple PST files. As an example, the expansion of a PST file to allocate more space on disk requires allocation in the Master File Table (MFT - on an NTFS partition). This is a blocking process, which locks the entire volume on the file server while it takes place, causing all other I/O to that volume to be queued. This results in a service interruption and potential server hangs to users storing PST files or other share data on those volumes. This is a known and well-documented issue which can be traced back to raw data from performance monitor reports.
Problem 3: File Sharing and Remote Access

PST files do not natively support file sharing between multiple users simultaneously. If you attempt to configure this, the mail file may be corrupted -- not to mention the fact you would need to run the file over the network, so problem #2, above, has already been invoked.

Storing data in PST files also has no benefits for remote access either. Exchange's Outlook Web Access (OWA) (or Outlook Web App, in Exchange 2010) allows users to remotely access their mailboxes, providing a near Outlook user interface for doing so. Data in PST files has usually been removed from the mailbox, so immediately becomes inaccessible to the user remotely.

Problem 4: Inefficient use of resources

You've invested in a powerful Exchange Server. It: has large, redundant disk arrays, processing power and RAM capacity; cost you thousands to purchase the hardware and software licenses; adds significantly to your energy and data centre cooling bill. If PST files are in use, your server is essentially going to waste; the functionality of the server you are actually using is essentially the same as a free Linux mail server distribution running on an old workstation supporting POP3 clients.

Problem 5: Legal Implications

With the release of Exchange 2010, the Exchange Server product group introduced some fantastic new features which make it very easy to enforce legal holds, retention and compliance across your company's users - or a subset thereof - if required to do so. Multi-Mailbox Search makes it very easy for a legal team to examine the content of mailboxes in the organisation, perhaps retrieving material in defence of a law suit or locating evidence to build a case against an employee. There are many such scenarios where this would be required. Another one of the features, dubbed "Dumpster 2.0", ensures users are unable to modify or delete anything from their mailboxes. Mailbox data is truly immutable, and every change is tracked.

Enter PST files. When the PST is in use, the data is removed from the Exchange Server and stored in local archive files scattered across your network. It becomes next-to-impossible to track what the user stores in those local files or locate information which could act as vital evidence in a court room. The overhead for such discovery skyrockets, as PST files would need to be located and individually examined, which is prohibitive in terms of cost and time for your legal team. If the user wishes to hide evidence, they can do so easily, without any possibility of data recovery.

These new features are a fantastic improvement to Exchange, but are only 100% effective when all of an organisation's mail data is stored within the Exchange infrastructure.

But...

Despite the considerations above, you might still be wondering how to work around those common problems which PST files are oh so convenient for solving.


Use 1: Archiving

This is a mis-conception, brought about largely by Outlook's desire to continue annoying its users with AutoArchive prompts. There is no reason whatsoever that mail should be archived to each user's local PC. Consider the actions you would take to archive files off your file server; where would you put the archived data? On your own PC? On your manager's? On the CEO's? You'd do none of those three, as the data is unlikely to be backed up, and you cannot assure data security. Instead, you'd find some space on a share on your archive server - or create a LUN using spare space on some SAN.

The same applies to email. Off-loading email from your Exchange Server to user PCs has significant risks attached to it. Instead, you should use an enterprise mail archiving solution. Previously, such actions would require the purchase of a third-party piece of software, but with Exchange 2010, the product group have again delivered: Personal Archives.

Retention and compliance serve their purpose in many industries which must assure the public that they are acting with integrity. However, as the amount of electronic data continues to grow, it becomes costly for an organisation to provision the resources to store such data in their central data centres. For Exchange, modern organisations might deploy one or more Exchange 2010 Database Availability Groups (DAGs), the clustered, highly available solution for ensuring mailbox data is always online and always available. The Exchange Servers which house mailbox data are likely to have very expensive disk subsystems, perhaps using a highly redundant configuration of 10k or 15k RPM Serial-attached SCSI (SAS) disks. The cost per GB of such storage can escalate very quickly, not to mention the RAM, CPU and power requirements for operating such environments, and the need to provision backups of rapidly changing mailbox data.

The Personal Archive feature in Exchange 2010 is one method of counteracting the costs of storing an exponentially increasing amount of data. Data which reaches an age suitable for archiving is generally accessed less frequently than the newer data in a person's mailbox. As such, it seems absurd that highly available DAGs are set aside to handle 5+ year old data. On Exchange 2010 SP1 and higher, it is possible to store a user's personal archive into a separate mailbox database which is hosted on a different set of servers within the same Active Directory site -- so-called tiered storage. Servers can be dedicated to the storage of archive mailboxes, and as such, have lower requirements in terms of their performance and disk configurations. You could reduce overhead by, for example:
dropping back to 7200rpm SATA disks in your archive servers, since the data is modified less frequently and is generally in less demand on a day-to-day basis
dispense with costly DAG configurations for archived data, provided it is acceptable that older data could be lost temporarily in the event of a server failure
run backups much less often, perhaps on a monthly rather than daily or weekly basis
The degree by which the infrastructure is cut back for archive mailboxes is a matter for an organisation to address internally based on their requirements. However, I can guarantee that the use of Personal Archives affords an Exchange Administrator and his/her compliance teams an improved level of access to corporate data. Multi-mailbox search can search personal archives in much the same way as a regular mailbox, making the compliance process a breeze in comparison to the PST approach.

From a user's perspective, personal archives are also much improved over the PST approach, as the data stored therein can still be accessed via Outlook Web App (OWA). Retention policies within Exchange allow the administrator and/or compliance team to control exactly when and how certain mailbox data is moved to the personal archive mailbox, removing the burden of archiving from the users and ensuring it is done correctly, every time.

Use 2: On the road

For users on the road, there is no need to store their mail in a PST file. Cached Exchange Mode has been available since the days of Exchange 2003 and Outlook 2003 and allows users to take a copy of their mailbox with them when they travel. When they reconnect to the network, the changes are seamlessly synchronised back to the server, including any messages they happen to write and send while in offline mode.

Use 3: Exmerge (Exchange 2003)/Export-Mailbox (newer versions)

This is just about the only use of PST files which I can agree to -- and I'll admit, I've used this approach myself in the past. If you migrate to a new mail system or rebuild your Exchange system, sometimes you cannot avoid using exmerge to take handy copies of the mailboxes - which can later be re-imported to the new system.

However, most corporations are unlikely to rebuild their entire Exchange infrastructure by taking it offline and formatting the servers. Chances are, you will bring new mailbox servers online before decommissioning the old ones. In this case, there is no reason to use the PST export approach to migrating data; simply use the Move Mailbox tools to migrate the mailboxes between servers.

Within the same Exchange organisation, a mailbox move is seemless and very easy to implement. If performing a cross-forest move, the requirements are slightly more complex, as you must provision user accounts in the new forest with the proper information before commencing a mailbox move. However, the process is really quite simple and has survived the test of time, and is therefore the preferred method of moving mailbox data.

Use 4: Home Users
 
These are the people who the PST is most applicable to. If you are connecting via Outlook to a Post Office Protocol (POP) host to download your email, that email will be stored in a PST file. The fact you don't have an Exchange Server doesn't change any of the points above, though; that PST is still susceptible to corruption. If mail is deleted off the server, this could lead to data loss.
 
For this issue, you really have two solutions. The POP3 account in Outlook can be configured to leave email on the server. This acts as a backup; if your PST file becomes corrupted, the ISP still has a copy of your messages, so they can be downloaded again. To configure, open the Tools > Account Settings dialog in Outlook. Select your POP3 account, choose Properties, press More Settings, then switch to the Advanced tab. Under the Delivery section at the bottom of the window you should check the "Leave a copy of messages on the server" checkbox. If you want a backup of all your mail, don't enable the option to remove it from the server after a certain time period.
 
The disadvantage to the POP3 solution becomes apparent if you move to another computer or access your mailbox via your ISP's webmail interface. The message state information (tracking of read/unread or whether the message has been replied to or forwarded) is not transferred back to the ISP, so all the mail you thought you had read and handled will still be marked unread on the ISP's server.
 
My preferred solution, and the one I use regularly, is an Internet Message Access Protocol (IMAP) account. The IMAP protocol is another mail protocol used to access email; it stands alongside POP. However, using IMAP, you replicate a client-server topology very similar to connecting to an Exchange mailbox with Outlook in Cached Exchange Mode. With IMAP, email generally remains stored in your mailbox at the ISP until you specifically delete it. Nevertheless, you can't get away from PST files completely; they are still there when you use an IMAP account, as Outlook uses them to make a cache of the data for working with the IMAP account in offline mode. However, as the PST isn't the only location where your data is stored, any corruption is not going to lead to data loss.
 
It should be noted that both the POP solution for leaving data on the server, as well as the IMAP solution, both have drawbacks, as items in your Calendar, Contacts or Tasks folders will not be stored on the server. IMAP does not support special folders - such as the Calendar or Tasks - and these will not be replicated back with a POP account, so you will still be using a PST file to some extent. Unless you move entirely into the cloud (use web services for email, calendar and contacts) or purchase your Exchange Server, you won't be able to easily get away from this.

Conclusion

I've covered a fair bit of information regarding PST files here. Hopefully, my points detailing why the use of PSTs is so impractical will now encourage you to reconsider your PST usage, archiving practices and retention policies.

With all your user mail stored safely on the Exchange Server, rather than local PCs, assistants can become delegates for their managers, looking after their mailbox; the administrator can rest assured that all data is centrally stored and backup up and you can turn off Outlook AutoArchive, relieving end users of that annoying prompt every couple of weeks.

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Author:tigermatt
59 Comments
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by:Kevin Cross
Nice Article, Matt!
Voted yes above.
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by:lherrou
Excellent article. Got my yes vote as well.
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by:Mark Wills
Hi TigerMatt,

I have been a mobile road warrior for over 15 years. During that time I might have had 20 devices, and thank goodness for the PST solution !

Not quite the same thought process for my little network...

So, it is not always so bad... Admittedly, there are a few more alternatives nowadays, and maybe needs revisiting as a result of your Article.

Regards,

Mark Wills
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by:tigermatt
Hi Mark,

Thanks for your comments. What I was really trying to touch with the article is the problem of using PST files in a corporate environment where an Exchange Server is employed, particularly for organisations who allow users to archive off to PST.

If looked after and frequent backups are made and stored, the PST solution isn't necessarily a bad one. However, it is susceptible to corruption, particularly when they start growing in size. I don't know what you used at your office when you weren't on the road, but if you had an Exchange Server, it would certainly have been more appropriate to run Outlook in Cached Exchange Mode.

Does that address your concerns? Yes, there are so many other alternatives today to the PST format, it is something users need to consider strongly about using before they go ahead and take the plunge.

-Matt
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by:joefreedom
Thanks for taking the time to put this article together, it's both informative and a good read.
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by:tigermatt
Thanks Joe! Your comments are appreciated. I'm glad you enjoyed reading it.
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by:evilrix
Nice article, voted yes above.
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by:Crolack
We ran into an issue that if a PST file was over 4GB in size, that the encryption software was unable to decrypt it.
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by:markmartens001
we ran into a problem regarding exchange cached mode with outlook. Without it and using .pst files everything works fine. With using no pst files and only exchange my outlook.exe process in the task manager fails to close. Maybe there is no road to glory with or without using .pst files/cached mode.
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by:Brian B
Should also add that if you are backing up and a user has their PST file open, the backup will skip over it. So no backup.
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by:koreansuper
hi Tiger Mart;
It is nice article and really helpful for deployment and migration. Thank you..
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by:tigermatt
koreansuper,

Thanks for your kind words.

TBone2K,

Good point - file locking does mean the backup won't take the file (presumably a backup of the local machine, not the PST in a network share... *laughing*)

Matt
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by:kaciuba
Just a quick note that 1and1.com (yea i know you hate them) offer an EXCHANGE mailbox solution. I have a registered domain name with a bunch of mailboxes. I upgraded just one of my mailboxes to an exchange mailbox and its the best. Push pull notification, outlook web access, the whole bit. kicks IMAP's butt.

Not sure if anyone else is offering it??
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by:tigermatt
Hi kaciuba,

Actually, I use 1and1 for a lot of my hosting, so I don't hate them! Many admins do though - and my larger sites are running on GoDaddy/Fasthosts hosting.

Any form of Exchange hosting will always be much better than IMAP. IMAP doesn't have the support Exchange does by far.

There are many other Exchange hosting solutions in addition to 1and1 - I think most major hosts are offering it (with varying degrees of support) by now.

-Matt
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by:Auric1983
I fight with PST files on a regular basis, recently had a notebook user lose their HDD and with it their PST file.  We only use it for mail archiving, but yeah what a pain in the butt!

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by:Jason C. Levine
Nice article, sir.  Reminds me why I chose Google Apps for the Domain instead of Exchange :P
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by:David Lee
Good article, Matt!
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by:joensw
Very Good Article
Interesting..
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by:knoxzoo
Yet more required reading for my interns.

Thanks!
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by:bains1000
Brilliant article, I have a customer who has an exchange 2007 server used heavily for email sharing.  They have a new employee who in his old employment would create PST files in their shared directory under the jobs they are working on and put all their emails relating to the job into a PST file.  This article will backup my reason for NOT wanting PSt files all over the network.

thanks.
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by:tigermatt
Thanks for all the recent feedback. It is much appreciated (and yes, jason1178, I won't deny that Google Apps has its advantages) :)

Matt
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by:ValentinoV
The annoying Outlook Auto-archive popup was the reason that I went over this article, quite interesting!  Now if only I could convince those admins :-)

Here goes another Yes vote, well done!
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by:tigermatt

Thanks for the support, ValentinoV! I appreciate it.

As it happens, you can disable the auto-archive or just completely remove PST support via the Outlook ADM/ADMX Group Policy templates. The general issues though are (a) convincing management there is good reason to do this (invariably they will have the largest PST archives and see no reason to change something which works) and (b) migrating everyone away from PST before considering implementing the change.

-Matt
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by:NEEDYITGUY
Sorry! Disagree! Disagree! and more Disagree!!!

I've been a IT Consultant / Network Administrator for over 18 years and have worked with Exchange 4.0 and on.  So, you can imagine that I've seen them all.  Since emergence of Office 97 I have used PST files extensively.  In dealing with over 100 different small to large companies, and 1000's of users, I have only had ONE case of corrupt PST, which idiot president went over 2GB despite of my repeated warnings.

FYI, currently, I have over 450 users in 3 different companies that I have their PSTs on the NETWORK drives since Office XP without a single case of incident.  They work on  network drives like a charm.  Yes, when there are "network problems" they don't have access to them, but, then again, when there are network problems, nothing works!
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by:FDiskWizard
@NEEDITGUY, and everyone else...

Take a look at this article.
http://blogs.technet.com/b/askperf/archive/2007/01/21/network-stored-pst-files-don-t-do-it.aspx

Which includes a link to the Microsoft article on PSTs over WAN (It's Unsupported)
http://support.microsoft.com/kb/297019/en-us

Maybe you've been lucky. we had an issue recently where 1 server was acting like it was out of resources. It turned out that one person had 30 PST files open. She closed them and all was well.
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by:NEEDYITGUY
@FDiskWizard: both articles you are referring to, have to do with .PST being the point of delivery!  I agree, and I never, ever user .PST files for MS Exchnage direct delivery.  I always have my users using them as "archive" folders and they all reside on the servers.  I DO NOT allow any local drive archiving. Every single user at every single company that I manage has MULTIPLE .pst files (mostly by year) stored on the network drives ( a couple of them on SAN) and as soon as they launch Outlook their Mailbox (point of delivery for sent and received items) shows up on the top and the .pst files at the bottom.  

To all pragmatic users and IT Guys, I assure you using .PST folders for archiving will NOT cause any problem with .pst corruption or slowing down the network!  Through experience, I have experienced Exchange servers being brought down by huge Information Stores (collection of all personal and public folders) 100's of times, but never, ever by .pst's stored on the network drives, not even once.  Considering 18 years of managing 100's of companies without incident as "luck" is complete lack of respect for stats.
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by:Auric1983
I'm not affiliated with these guys in any way, so far my only experience has been using it as part our Exchange implementation, but if anybody is looking for a cost effective solution to replace PST files in a SME environment.   It stores all the mail in a SQL database (or Firebird if you are small)  

GFI MailArchiver: http://www.gfi.com/mailarchiver 

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by:slyman_19
Excellent eye opener!
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by:CATHY-IT
Curious how this effects users connecting to a Terminal Server and running Outlook  2003 on it and having a Personal Folder *.pst file that are saved on Terminal Server within the local profile for each user? Are these PST Files less likely to corrupt and/or cause network speed issues in comparison to someone running a PST on there Local workstation copy of Outlook  that is actually on the server via a Mapped drive?
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by:NEEDYITGUY
@cathy-it: In my opinion, if you are using PST's for "point-of-delivery" for Exchange Server and the PSTs are located on a location other than the "local" (which in case of TS the profile of the user is local for that session of Outlook) then you will have problems.  However, if you are using their "Mail Box", which is an integrated part of Informatioin Store and using PSTs just for offlloading sent/rec items on them, it really does not matter where the PSTs are located.  I like my users to use the PST's only for archiving and I demand putting all on one of the servers so they can get backed up and less prone to crashing due to fact that most servers have a built-in raid.

Let me know if this does not make sense to you.
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by:CATHY-IT
Some users have added Personal Folders to their Outlook in addition to the Mailbox within Exchange Server which is the point of delivery. they then move the emails they want to keep into their personal folders area to save them for future use or reference, Alot are using Outlook on their Local Desktop and therfore saving their PST on their C: (not getting backed up). Have a few, due to being remote alot that work only on the Terminal Server and also do the same as above but since their PST files are on the Terminal Server they are getting backed up. I'm trying to decide what to do with all the ones that have their PST's on C: of their workstations..I need a solution. I was even considering setting up Profiling and then changing the default location of the PST in the registery so that its saved in an directory that would automatically be copied up to the server at log out with Windows Profiling, I've done this at my previous job, but no one was mobile there.. Here we have alot Users on move with laptops. On the fence and researching for simple to deploy options. And then this article has me wondering if we should get away from using PST all together for archiving emails.
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by:tigermatt

NEEDYITGUY,

Thanks for your comments. I've not had the opportunity to respond to them until now due to other commitments and arising issues, but I did read and digest them at the time.

One of the key points I noticed in your first comment above was:

>> I have only had ONE case of corrupt PST, which idiot president went over 2GB despite of my repeated warnings

That's one of the most prevalent issues any IT professional ever encounters: the end user. You cite that the president went over 2GB and thus received a corrupt PST file; I'm not to know whether you managed to repair the file and get that data back, but let's assume in this case it was lost.

In that circumstance, the limitation of the PST format came into full play - user goes over 2GB, user loses data. I know that very few of the 2500+ users I look after on a daily basis would be inclined to go check how big the file was before they started archiving data and then calculate the size of the data being archived before hitting the button. Other pressures mean it just won't happen - and even if it did, it costs the company time and money.

Providing warnings to the end user that this would happen was a very wise move; at least you're not responsible when they do lose data. However, I wouldn't want to provide my users with a facility so prone to corruption - I want to remove the user out of the safety loop and provide a highly robust and reliable system which doesn't rely on them to continually monitor it. The IT staff are the ones adept to monitoring servers and systems and responding to issues to keep them stable, not end users who sell things or manage HR. That's why I would recommend a tool like GFI MailArchiver, as mentioned by a previous member, or in Exchange 2010, you can hit the new personal archives. These are centralised, enterprise solutions supported by enterprise people who aren't in the business of losing data.

With the relative cost of disk storage falling all the time and the recent release of Exchange 2010, the TCO of running mailbox servers with ever increasing storage capacity has dropped considerably. We're not actually using shared storage for Exchange any longer; just individual mailbox servers to store user data. We can supply tiered storage to separate the old archived data from newer inbound content - the personal archives can be supplied on less redundant servers which are backed up less but still make that data available at *any PC* that user sits down at. PST files can't do that, and they certainly make it difficult when using remote access.

With PST files, you also have the issue of compliance. Once again, this would be a huge job when using PST files. With centralised solutions built-in to Exchange, we can still perform discovery searches, litigation hold and automated records management across all that data. With PSTs I can't think of a feasible way of doing this which wouldn't break the bank in terms of manual work and the time it would take.

Microsoft make it very clear they do not support PSTs on a network location. I appreciate there are many who might have avoided this requirement and never had an issue. However, I'd consider myself foolish to bypass a product support requirement stipulated in the documentation, and one which has resulted in data loss. That it worked in the past doesn't mean to say it will continue to work now or in the future - and since Microsoft aren't going to test their software with networked PST files, there's no knowing what problems lie out there to break the system. Even if you did use local PST files to negate the network issues, there's always the issue of a user moving their PST around themselves which leads to an elevated prospect of data theft.

I can fully appreciate where you are coming from. A topic as controversial as this will always experience some resistance. The real problem here comes down to company requirements and whether they are willing to explore solutions which seem costly on the surface, but actually reduce admin time in the long run. It also depends on whether you are happy to avoid software support requirements, which I am not.

-Matt
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by:mediamail
very helpful - thanks.

Dan.
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by:NEEDYITGUY
Well folks, the "debate" here is not for showing who knows more and who's right or wrong.  If I have to draw one conclusion from all of this, it is about the paths we choose to manage our networks.  Before I delve into responding to the more specific issues expressed by Matt above, let me set some of my fundamental policies when it comes to IT Management (more specifically, Network Administration).

1- I manage small to medium size companies, therefore, network / system / user management are intertwined in my daily activities.  We can debate all we want as to how Microsoft, Nintendo, Boeing, ... manage their networks, but my world is galaxies apart from theirs.

2- I despise the use of any "3rd party" solutions for the following reasons:
   - Costly for most of my clients.
   - Costly to me in terms of installing, configuring, monitoring, upgrading, trouble-shooting, and utlization of my network resources.
Therefore, I avoid them as much as I can and I try using the built-in features of my O/S.  For example, I have never used any 3rd party backup software.  I love ntbackup and I have used it extensively and in 100% automated environments using little batch files which I write myself.  I have recovered databases and MS Exchange a few times by falling back on my impacable backups!!!

3- We are talking about MS Exchange 2003 here and not 2010.  2003 is still 70-80% of the market.

4- I do not believe in "baby-sitting" my users!!!!!!!!!  I pride myself in providing regular training sessions or 2-3 min online ones in order to make them as self efficient as possible.  They must learn how and where they can look under the hood and what to look for.

Matt, of course I was able to recover the crashed pst.  I am not sure why you still do not separate your take on pst as "Point of Delivery" for new incoming emails vs. using them as archive folders.  I agree with you 100% that I will never use the pst as the "Point of Deliver" and leaving them on the network drives (100% OK if on local drive), however, using the pst for archiving and leaving them on the network drives so they can get backed up has been bullet-proof since 1997-8 for me.

regards,

NEEDYITGUY
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by:FDiskWizard
NEEDITGUY, when I posted earlier with a couple of links, you said those articles were talking about PSTs as a delivery. The author did give one scenario about a bunch of users having a PST as a delivery location, but the article went deeper than that. That was a
Mainly I saw Microsoft saying:
   PSTs on file shares: DON'T DO IT. Period. Not Supported. And reasons why.
That article was from the Microsoft Performance Team.

We've ran into several cases where PSTs were causing the file server to start running out of resources. Which meant people couldn't browse to a share, open files, save, etc...
I proved it, at least on one, by closing the 30 PST files one lady had open. Everything immediately returned to normal. That was a server in a small office. But that one person loved PST files.

So, can you use PSTs on a share? Yes. Without issue: Probably not.
As PSTs have gotten bigger and bigger they seem to be causing more issues. The lady with 30 x PSTs was averaging around 500MB each I think. Some over 1GB.

I have also seen a number of people using them as a semi-delivery location by moving the emails to a PST after it arrives. They keep saving, and that PST files have to GROW... that article mentions the performance impact when allocating additional space. Which is probably why using for a PST for delivery is a REALLY bad idea.
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by:Auric1983
@FDiskWizard,

I have users with 5gb+ PST Files that I'm struggling to get rid of now...  

We're starting to use MailArchiver and SQL as a replacement,but it's been a long time coming.
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by:FDiskWizard
We're using an archive system. But it has no folder organization. So, many users still keep emails in PSTs. I have seen many larger ones also. I try to stomp them when possible.
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by:Alan Hardisty
@NEEDYITGUY:

>> To all pragmatic users and IT Guys, I assure you using .PST folders for archiving will NOT cause any problem with .pst corruption or slowing down the network!  <<

Well - I have to completely disagree with you there as I have had two customers doing exactly what you say is possible and guess what - their archive .PST files are stored on the server and they are Autoarchiving to them and the backups are failing due to corrupt .PST files (their archive files).

I got them to move the files back to their local PC's, repaired them, copied the files back to the server and left a local copy on their PC's for them to archive to, then regularly copy them to the server - problem solved.

Just because you have not encountered the problem - does not mean it doesn't exist.

Matt's advice is spot on as usual.  Ignore him at your peril.

Alan
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by:NEEDYITGUY
@alanhardisty

"Just because you have not encountered the proble....." Well, my dear colleague, may be you overlooked the fact that I have been a hands-on IT consultant / network engineer / system administrator for over 18 years and at a point I have over 20 active businesses as clients and currently managing a handful with over 500 uers.  Again, as you said, it is your prerogative to follow your instincts or logically bank on experiences of others.  Funny part is that it sound like you have not read the original argument Matt presented.  His original article talks about using .pst's as point of delivery, not as an archiving folder.

"Matt's advice" was ignored before knowing it was "Matt's advice", so, if you are a Matt's fan, you don't need to take it personal. :-)
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by:Alan Hardisty
I'll see your 18 years and raise you to 22 years (about 22% longer than you have).  You have 20 active businesses - I have about 100 and support over 40 servers - so what?

You haven't had problems with .PST corruption - the customers who I support and who have put .PST files on their server and some access them directly on the server, have had issues and the .PST file have been corrupted as a result.  Those that store .PST files on a server and also a local copy of the same file on their local PC and access the local copy, don't have issues.

I'm referring to the following section (not sure what you are referring to):

PST files must be stored on a local hard disk. Accessing them over a network is not supported by Microsoft. Instabilities in the network, loss of network connectivity, speed issues in reading and writing from the file server can all cause issues -- particularly for sensitive PST files, which are so very easily corrupted.

When following this advice - no problems - when not following the advice - problems.

>> if you are a Matt's fan, you don't need to take it personal <<

I don't take things personally - I'm mature enough not to.

Alan
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by:Em Man
What Happen if You have your Boss who is receiving large number of emails everyday and are located in other country? 20GB capacity of his Mailbox?

How will you handle this kind of scenario?

This was being tolerated by previous admins before me.
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by:etech0
As a home user, what can I use instead of pst?
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by:pcs3658
I am a independent financial consultant, I receive lot of email, which I always take a back up, there is no other alternative.  so I take back up myself but its pretty hard to find pst files in Outlook 2010 /Windows 7
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by:MikeXna
Good Article. It details all of the cons of PST's.
However, PST's have pros too, such as the ability to create and organize email into folders.
Yes, you can do this under your mailbox too, but what is a user to do when they run out of space?  Web based archive platforms are good at saving old email but in my experience, they are slow at searching and do not allow you to organize by subfolder. Anyone know one that does?
I am stuck in the middle on this issue.
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by:tigermatt
Thanks for the comments, MikeXna.

You're right. PST is a great, simple solution for making up for a shortage of space when a user's mailbox grows full. It also clears space out on your Exchange Server, which means you can store even more email.

However, many companies rely on historical email for business purposes, perhaps in keeping with record keeping legislation or just for business archive reasons. To be honest, I keep virtually all email - you never know when something could become very useful.

To that end, storing in PSTs becomes a huge disadvantage to you. The data is largely at the user's control and, as I've covered, is highly susceptible to being lost, corrupted or destroyed.

The solution here really is to upgrade the storage in your Exchange Servers when the time comes that users begin to run out of space. Storage today is not expensive. Plus, if you look at the costs of more storage versus loss in business should historical data be lost (or legal proceedings if you break a legal understanding to retain data), you will quickly arrive at the understanding that upgrading storage is many orders of magnitude cheaper and less risky.

I would not do anything different, and I don't tend to be an advocate of any online archive platforms. I mentioned in the article that readers could look at Symantec Enterprise Vault, but I don't endorse this either anymore, since Exchange 2010 added Personal Archives to the feature set.

In large organisations, it would therefore be common to provide users with an "active" mailbox and then an archive mailbox. The later service packs of Ex2010 add support for an archive mailbox to be situated on a separate server. This is typically deployed so that it has less or no redundancy, provided this is acceptable for the operation of the business, and is backed up less, since the data does not change very often. Depending on your users' usage patterns, you may also be able to cut down on hardware requirements; if users do not hit their archives much, then you don't need such fast spindles, you can probably dispense with some of that RAM and dedicate CPU cycles to some other more critical service.

For smaller organisations who don't have the requirement for separate archive storage, then just add storage to the main Exchange Servers, and you can't go wrong.

That's my take on how to avoid PST. There are very few cases in which I find a legitimate need to use them. In general, if you do find a need, there is probably a better way.

-Matt
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by:tigermatt
etech0,

>> As a home user, what can I use instead of pst?

In the first instance, look at whether your ISP or mail provider supports IMAP. This means all email is maintained at the server, and only a local cache is stored on the local machine. Yes, the local cache is a PST file, but this is not the only copy of the data.

Contacts and calendar will sadly be stored locally in a PST in this case, and there is no way around that.

If you are more of a power user, then you might consider buying into a hosted Exchange subscription from one of the major hosting companies. You might need your own domain name, but this means you benefit from a full Exchange experience, and ALL your data will be stored on a secure Exchange installation.

-Matt
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by:etech0
I am a power user, but not really looking to spend money at this point. I just switched from POP to IMAP for various reasons (mostly so that I can access my email from anywhere), and it's extremely slow in Outlook 2010. Do you know why this could be and what I could do about it?
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by:AaronCaito
@MikeXna

I've been using Google Apps for mail hosting for my clients that need to store lots of mail and organize it neatly.  Google also does a pretty good job with search.
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by:cgustaf
About the funniest question I've heard in a long time:  "Errr...Has anybody seen my PST file?"

True.  Being auto created one easily looses track of 'em suckers!
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by:bit_rot
Excellent article! Found lots of useful information in this post that I will share with the rest of my team. Thank you for taking the time to write this!
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by:tigermatt
bit_rot,

That's very kind of you to say. Thank you for your feedback. I have just recently added some additional detail to the section on running over the network (specifically the impact on a file server this can cause) which you (and all the other readers of this) may find useful.

Thanks, all!

-Matt
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by:benchapman
PST's are evil and can and do bring networks to their knees when running unsupported. PST's over WAN's are even more evil and highly prone to corruption due to network interruptions. If you allow PST's locally, have a backup script to copy them to the servers regularly for backups but dont connect to them from Outlook on network shares. There used to be a Microsoft plugin for Outlook called PSTBackup that used to do it for you. Not sure if it still exists. I don't allow live PST's on any network share period and regularly run scripts to enforce it.

For home usesr, IMAP used to be fine but is complete rubbish compared to Active-Sync (especially once mailboxes get over a few GB if your ISP will allow it). Hosted Exchange direct from Microsoft (I hope they can run their own product well) is a few dollars per month for a 25GB mailbox. Stick with the junk if you want but my time is too valuable to deal with the hassles. Perfect sync across two PC's, a Mac, an ipad, an Android phone, a Nexus 7. Job done. Google Apps is still not quite there (IMHO) but it wont be long and as Google have adopted MS Active-Sync themselves then that is validation that MS got it right.

GFI MailArchiver does a good job of keeping mail store sizes down but has anyone ever tried to uninstall it now the Exchange 2003 STD size limits are not an issue any more with 2010? World of pain.
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by:David Carr
Interesting take on eliminating PSTs. I have seen corruption and server issues and even Outlook issues when accessing PST on a network.( I know it is not supported and not my choice).

I have seen PST on local drives with script to copy PST files to server for backups. I support bigger user mailboxes and Outlook training for end users. A few places I know block PST creation once an Archiving solution is implemented but I would recommend that approach only with a robust archiving solution.
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by:telyni19
Some companies only allow a limited amount of space in the online mailboxes for each user. For us, it's 100 MB standard, expandable up to 500 MB under special circumstances. MB, not GB. These days, with 2-5 MB attachments very common, that goes very quickly. Therefore we're forced to archive everything to local PSTs, and many of my colleagues still run into the limit often, resulting in email bouncing because their mailbox is full. I have to make sure to keep up with email even while on vacation because otherwise my mailbox will fill up and I'll lose messages.

So I maintain one primary local PST for active email, which I file right away after I'm done with it. Then I allow Outlook to auto-archive that to a second file, but every few months I compact the active PSTs and make sure they aren't too much more than 2 GB, and if the latest archive is getting large, I start a new one. I also backup daily to an external but physically local hard drive (not network). I've never had any PST corruption. It's not ideal, but as an end user in a large corporation with tiny mailbox limits, there isn't any other practical way I know of to manage my email volume. One time I have had to extract a relevant set of messages out to a separate PST to make them available for discovery in a lawsuit though.
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by:renami86
thank you
it,s very helpful
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by:pbarcia
very good reference...
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by:Marshal Hubs
Good resource
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by:Trancebolt
There is an acrobat plugin when you install pro that has an autoarchive certain pdf parameters options... Which relates to telyni19's comment.

I agree with NEEDITGUY and the author on many points; and it matters not how many servers you run sirs... at least in terms of prestige. I run one of them, so my automation needs are lesser... and i have more time to devote to my people. So i understand not all of my points will mesh with you

But however, I think two points need to be returned to the surface.


>The "point of delivery" comment was related to running on 'Cache' mode right?

Wherein your setting up the accounts exchange info... and its a little checkbox under the server url..
I think it just downloads a copy of all emails to your pc to let you have instant access to them without using net/pc energy to read emails that arent new.


>Are you speaking of PSTs only in the sense of archives?
because i use an exchange server at the office and all emails are downloaded to psts and archives are locally created... I just disabled their abilities to make them, and then I go and create them myself and move them to a storage place.
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by:Caltor
"Accessing them over a network is not supported by Microsoft, and has not been since Exchange 4.0"
PST files are generally used without Exchange so this sentence doesn't make sense to me. Surely it should cite an Outlook version.
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