Exchange database for reliable recovery

After a recovery operation is completed, Exchange checks whether transaction logs exist on the server. If the transaction logs exist, they will help the latest status of the recovered database updates. Exchange will compare the update serial number of the objects stored in the database USN) with the USN on other servers. If the USN status on the server is newer than the USN status of the just-recovered database, the database is automatically updated based on the new USN. The final result of such a series of operations is that the status of the recovered database is basically the same as that before it crashes.
This is a magic technology hidden behind the restoration process. I am very grateful to Microsoft for its efforts in developing this technology. However, in some cases, the Exchange data recovery method may be different from your ideas.
The restoration process I described just now is performed if the server cannot work, but this is not the case in many cases. For example, if your company's email system administrator is a new Tom and accidentally deletes one thousand emails, you have to restore the system, but the reason you do this is not because the server cannot work.
Suppose you created a system backup last night. This morning, your head administrator suddenly deleted one thousand mailboxes. Yes, you can recover the backup last night, but here is a problem: the delete operation has a new USN than the data you backed up last night. That is to say, after you restored the backup last night, yes, the mailbox is restored, but will soon be deleted, because Exchange considers that only these mailboxes can be deleted to ensure that the database can be restored to the latest state.
To solve this problem, Microsoft released a tool named AUTHREST. EXE. This tool allows you to perform reliable recovery operations on the Exchange database. It can modify the USN of the database to be restored to ensure that they are newer than the USN of any other Exchange Server. In this way, your recovery operation will overwrite anything on the server, that is, you can restore the one thousand mailboxes without worrying that they will be automatically deleted.
Obviously, AUTHREST. EXE is a useful tool, you should keep it at hand, but there are also some places to Note: Due to AUTHREST. EXE will update all USN information on a server, so some useful changes you made after the last backup will also be unable to be restored for this reason.
So how do we decide when to use AUTHREST. EXE and when should we not use it? If one thousand mailboxes have been deleted as described in the previous example, I will not hesitate to use this tool unless I have a very new backup. On the contrary, if your recent backup was made a few days ago, or you only need to restore a few mailboxes, you should choose to use the normal recovery method.
In this case, we recommend that you use the restore storage group function of Exchange 2003. With this function, you can restore your backup to a recovery storage group, instead of completely overwriting the existing database. Then you can move the deleted mailboxes from the recovery storage group to the information storage. This method may be a little more complex than using a recovery program, but it is much more effective.