PST vs OST: A Detailed Comparison

Personal Storage Table (PST) and Offline Storage Table (OST) are two file formats used by Microsoft Outlook for storing user data. Both have unique characteristics and serve different purposes in email management and data storage.

What is PST?

PST, or Personal Storage Table, is a file format used by Microsoft Outlook to store copies of messages, calendar events, and other items. PST files are most commonly used for storing archived items and are a popular choice for data backup and transfer.

Characteristics of PST Files:

Portability: PST files are portable and can be transferred between different computers or Outlook installations.
Usage: Primarily used for archiving and backup. They are not tied to any specific server or account.
Accessibility: Can be opened and accessed without an internet connection.
Size Limit: Older versions of Outlook have a 2GB limit, but newer versions support larger files (up to 50GB).

What is OST?

OST, or Offline Storage Table, is a file format used by Microsoft Exchange Server, as well as the Outlook and Office 365 suite. OST files are an offline cache of what is stored on the mail server, allowing access to mail data even when not connected to the internet.

Characteristics of OST Files:

Sync with Server: OST files automatically synchronize with the mail server when a connection is available.
Usage: Primarily used for offline access to mail data and real-time synchronization with the mail server.
Dependency: Tied to a specific mail account and Exchange server.
Size Limit: No fixed size limit, but performance can degrade with very large sizes.

Comparison of PST and OST

Feature	PST	OST
Portability	High (easily transferred)	Low (tied to specific account)
Usage Scenario	Backup, Archive	Offline Access, Synchronization
Internet Requirement	Not required	Required for synchronization
Server Dependency	No	Yes
Size Limit	Up to 50GB	Unlimited, but performance varies

Conclusion

Choosing between PST and OST depends on the user's specific needs. If the goal is to create backups or transfer data between different systems, PST is the better choice. For users who need to access their mailbox offline and synchronize with a mail server, OST is more suitable.