Microsoft designed .pst files with the objective of allowing a user to maintain local copy of their email messages on computer. When not configured to Microsoft Exchange Server, PST is basically a message store. But they cannot serve as an enterprise solution and prove unsupported over a WAN or LAN link. If you attempt to save it over network, in most of the situations, it gets corrupt and becomes inaccessible. Thus, it is recommended to opt for different solutions when you require a shared message store. However, in case of PST file corruption, you can scan and repair your damaged file using PST Repair tools.
In an enterprise environment, you can although specify UNC (Universal Naming Convention) or network directory that could act as the storage location for PST file, but saving the file directly on a network link introduces file corruption errors in it.
Basic Reason why PST is unsupported over WAN or LAN link
Different data access methods used by Microsoft Outlook and operating system
Contrary to the method that WAN or LAN links use to access data, PST files use file-access drive method. WAN and LAN links use network-access-driven methods. In file-access-driven method, computer system uses certain operating system provided file access commands in order to read/write data to the file. However, in network access-drive methods operating system provides similar commands, but for sending or receiving data from a networked computer system.
Now when you store a PST file over a network link, Outlook and operating system access data in dissimilar ways. The same file is simultaneously tried to read/write information using file commands and network commands. As a result of this, it takes a large amount of overhead and time to access data from PST file increases. You might observe delay in performing operations. In addition, the write operations take about four time longer time than read operations. Also if connection fails or degrades, it could result into damaged PST file, which requires PST Recovery solutions.
An Example of slow performance
You send an email message to about 100 different users, having same PST file as the delivery option that is stored on a file server. Suppose for receiving the message, few of these users need to extend their PST files which requires an extra allocation on disk using NTFS. While it occurs, it locks the whole volume. This is because while this, MFT is updated and free space is allocated. So, for each user, all other 99 users have to wait for performing I/O operations.
The above example shows that when you store PST file on a shared network, it might stop responding for a long interval of time. Thus, you observe several problems occurring at client sides and the basic reason is server queuing.
PST Corruption
The server services uses work times to perform tasks like extending the PST file. The work times use nonpaged pool (NPP) of kernel resource to get the required space After these work times get queued up, these are handled by server service worker threads. The disk subsystem gets all I/O requests, which are sent by server service. Now if disk subsystem fails to respond in time, all requests get queued up in the server work queues. For any reasons, if network failure occurs or degrades while these requests are queued up, PST gets affected. It could get corrupt and inaccessible.
Solution
• For PST Recovery an inbuilt tool is available included in Outlook installation- Inbox Repair Tool, also known as scanpst.exe. The tool is located at Hard Drive Letter:Program FilesCommon FilesSystemMSMAPILocaleID (which is 1033 for the USA or similar) in Outlook 2003 and earlier versions. In Outlook 2007, it is located at Hard Drive Letter:Program FilesMicrosoft OfficeOFFICE12
• If Inbox Repair Tool fails to repair the damaged PST file, you should use commercial PST Repair applications. These are file scanning tools for damaged PST designed with advanced technology to repair PST files. Such application perform safe and complete repair and provide safe restoration of data. You can use these products in any case of PST file corruption.
Stellar Phoenix
Outlook PST Repair is the comprehensive product built with powerful technology to repair and restore damaged Outlook PST file. This is a read-only
PST Recovery tool that supports file repair for PSTs created with Outlook 2007, 2003, 2002 and 2000. With advanced repair options, interactive interface and complete documentation, it is compatible with Windows Vista, XP, 2003, 2000 and NT. It also offers PST password recovery and Split PST functionalities.
