What Is MS Outlook?
MS Outlook or Microsoft Outlook is a personal
information manager that comes as a part of Microsoft Office Suite. Even though
being popularly used as an email client, it also comes with other very helpful
features such as the calendar, contact manager, task manager, notes and web
browser. Although being a part of the MS Office suite it can be downloaded
separately. It can be used as a standalone application as well as with MS
exchange Server and MS SharePoint Server for multiple users in an organization, a few common examples of their integration
are: shared mailboxes, calendars, Exchange public folders, meeting schedules and SharePoint lists.
As we start using
MS Outlook, all our emails, tasks, calendar and other such items are saved on either
a mail server or on our computers, or both. The MS Outlook data items saved in
our computer are stored in MS Outlook data files, that are, Personal Storage
Table (.pst) and Offline Storage table (.ost).
What are the Data files in MS
Outlook?
Before moving further with the data files we
should first get familiar with following encodings:
- ANSI data files
- Unicode data files
ANSI data file format
An ANSI data file (.pst or .ost) format is a
standard maintained for data file that is given as per the American National
Standard Institute, which has a file size limitation of 2 GB (231bytes).
If the size of the file exceeds this limit the data might get corrupted.
Moreover this is an 8 bit character encoding format hence, causing the system to slow down. This is why the
development of the Unicode encoding came into picture.
Unicode data
file format
Unicode data file (.pst or .ost) format can be
defined as the improvised version of the ANSI format. It has overcome one of the
biggest problem i.e. file size limitation to 2 GB in ANSI format. Moreover it
is 32 bit character encoding format, because of which it support multiple
character set and has no limit for the no of items per folder hence the user is
free to save his data without any worrying about the data size.
Now as we are familiar with the data encodings
we can very easily understand the two file extensions in MS Outlook:-
- PST files – Personal Storage Table data files
- OST files – Offline Storage Table data files
The Personal Storage Table (.pst) data files
are used as the data file in MS Outlook for accounts that are synchronized with
Outlook where as Offline Storage table (.ost) is created when we activate the
cached mode while configuring a new mailbox while we are using it with
Microsoft Exchange Server.
A further description of the data files is
elaborated in the Q/Ans. Below:
Q: What are PST Data files in MS Outlook?
A: PST is an abbreviation that is used for
Personal Storage Table. In MS Outlook the messages,calendar and other data items are saved in PST files in
short we can say that a PST data file is store room for all our outlook data
for a particular account. The PST file is usually used to store archived data.
The file is enlarged by a particular amount of bytes that is done by the use of
a fixed block based allocation scheme. This file then internally keeps a record
of the information about the non allocated and allocated blocks. So, whenever
any data file like email message or any noteis added to a PST file, the mail
client automatically adjusts the file size of the PST file.
2 GB
File size limit
Until
the introduction of MS Outlook 2003 the PST files were having a limitation of 2
GB i.e. as soon as the size of a PST file reaches close to 2 GB the Outlook
starts to slow down and as the size reaches 2 GB the data files got corrupted. The
main reason for this was till 2002 version of MS Outlook,it used the ANSI character
encoding that i.e. American National Standard Institute that was limited up to
only 2 GB data storage capacity. This was one of the major drawbacks of MS
Outlook.
Seeing this as a major problem, Microsoft gave
a solution to this problem in the form of a compression tool: Exchange 2000
tool - PST 2GB. But this tool also had a drawback. It compressed the PST file
by truncating the data and creating a copy of the original PST data file. This
truncated copy did not have all the data resulting in loss of data. Hence this
tool didn’t prove to be a complete solution to the problem.
So in order recover the lost outlook
email data the users had to either get a technician or use a third party
tool. The lost data can be Email, calendar, journal, task list and so on….
Q: Where are the PST data files in MS
Outlook?
A: The location of the PST data files may vary
according to the windows version that we are using. So accordingly the
following paths are defined as per the windows version:
- For MS Outlook 2013
- Windows 8:
- Win 7/vista:
- Windows XP:
- For Other versions
- Win 7/8/vista:
- Windows XP:
Q: What are OST Data files in MS Outlook?
A: OST is an abbreviation used for Offline Storage table data file. These files are created when our MS Outlook is configured with an Exchange Server Account and while configuring a new mail account we have used the cached mode option. When we use Outlook with Exchange server all our emails, journals and other items are delivered and stored on the server. The Outlook data file (.ost) keeps a copy of these data on our local machine. The cached exchanged mode allows us to work offline and whenever there is no connection with the exchange machine. The Outlook data file (.ost)is synchronized with the exchange machine as soon as a connection is established.
Q: Where are the OST data files in Outlook?
A: The location of the OST data files may vary according to the windows version that we are using. So accordingly the following paths are defined as per the windows version:
- For windows 8/7/vista
- For windows XP
