XADM: Option to Zero Out Deleted Messages on Exchange Server

When a message is deleted on an Exchange Server computer, there is currently no provision to zero out the deleted items. This means that the deleted data could be retrieved using conventional retrieval methods.

Microsoft recognizes the need for an option for zeroing out deleted items. We have modified Exchange Server 5.5 so that it is now possible to zero out the deleted items on a hard disk.

To obtain this feature, obtain the latest service pack for Exchange Server version 5.5. For more information, please see the following article in the Microsoft Knowledge Base:
This feature was first included in Exchange Server 5.5 Service Pack 2.



Zeroing out of pages has been made a part of the backup procedure. The backup will be a little bit slower, but it will also do zeroing work. However, the zeroing will occur after the tape write. This means that the deleted items will be on the tape until the next backup.

In order to work around the problem of the tape retaining the information of the deleted items, an option to run backup to a NULL device has been provided. This procedure will explicitly zero out pages but with no backup. To make sure that the tapes do not retain the information of the deleted items, it is suggested that the NULL option be executed before the actual tape backup. This will mean a read of every database page, but this is at the rate of approximately 60 gigabytes an hour. Thus, backup time will be increased for the time to run to a null device.

The NULL option is an extension to the Exchange backup API. A particular backup application may not support this function. At this time, NT Backup does not leverage this function.