Some times, when a large number of people are working on the Exchange server as a groups, their OST files become heavy in size as the number of emails exchanged between the group members increase. When OST files become larger than 2 GB, Microsoft Outlook sometimes encounters problems in loading the OST. Here is a detailed guide on how to repair such OST files in order to make them accessible.
OST files are offline storage files that store emails exchanged between the members of a group on the Exchange server and between other members of the organisation. OST files can be accessed to view emails and conversations when the user is not connected to the internet. Microsoft Outlook is responsible for managing emails of organisation on the Exchange server, providing services like Calender, Contacts and Tasks, apart from traditional email services. The need to recover OST files arises when the files get damaged and become inaccessible to the user. Most of the times, OST files get damaged due to their massive sizes, exceeding 2 GB, which is the limit imposed by Microsoft for OST and PST files. The problem cannot be solved using the Inbox Repair Tool offered by the company. The tool focuses on repairing damaged files but repairing files exceeding 2 GB is beyond its abilities. IT admins are advised to use the Inbox Repair Tool to create a truncated copy of the OST file before proceeding with file repair. Users are warned that even if the file is repaired, some of the might be lost in the process. This due to the fact that the tool reduces the size of the damaged OST, bringing its size 20 to 25 MB lower than 2 GB, leading to deletion of some of the data. Now, in order to start the process, users would have to first download the Inbox Repair Tool from the Microsoft Download Center. Then users can proceed by creating a truncated copy of the OST files in question. This can be done by the Pst2gb.exe program, extracted from the Inbox Repair Tool download files, which allows the users to shave off the amount of data which is required in order to recover OST files. Now, once the truncated file is created, IT admins would again have to access the Inbox Repair Tool and repair the now small OST file that has been created. After the process is completed, try opening the repaired OST file on Microsoft Outlook. If it fails to open for some reason, then delete the file and repeat the truncating process until an accessible repaired file is created. If the file open in Microsoft Outlook, then IT admin would need to right click on the root folder of the OST file and click on ‘Properties’. Click on the ‘Compress Now’ option in order to compress the repaired OST file. Depending on the size of the file being compressed, the process is most likely to take around four to eight hours before it is completed. Apart from using the steps and tools offered by Microsoft to recover OST files, IT admins can also use the DataNumen Exchange Recovery tool in order to recover the damaged files. In order to avoid further cases like this, IT admins can install a hotfix that prevent MS Outlook from allowing OST files to expand beyond 2 GB. Users can also use more than one OST file to distribute the data among them or they can also store email attachments in a file system and delete them from the messages.