Exchange Server users must be aware of any early signs of failure that indicate data corruption or loss. In fact, it is hard to build an always-consistent database. Sudden server crashes or improperly-done shutdowns, for instance, can create inconsistency in EDB due to data being failed to be written to disk. Exchange Server failure can be in two forms: physical corruption or logical corruption. Both have different signs, tools and techniques of EDB repair.
EDB repair for Physical Corruption
This form of corruption refers to any failure on the disk or other hardware-related problems. The failure can seriously cause fatally, destroyed data, which leads to data loss. So, it is important to notice early signs of failure and address any problems associated to them rapidly. As it relates to hardware, the most possible prevention is laid on the selective choice of the hardware as well as the configurations. Additionally, you also have to prevent any use of file-level utility that works against EDB as well as log files such as antivirus software. If failure detections are too late and corruption is occurring, you must restore the database from the latest backup and let the log files create a consistent state of the system. However, if the last backup comes with errors, it seems that an EDB repair is going to be useless. Perhaps, you think of running the Eseutil.exe to push the database to function again, but the damage it costs is just as bad – it deletes bad pages anyway.
EDB repair for Logical Corruption
This corruption is no longer associated with hardware, but database, such as database engine failure. The corruption may occur at varying levels: messages, mailboxes, attachments, and folders. Each level of corruption creates specific problems. For instance, application-level corruption creates inaccuracy in access control levels, reference counts, message headers, etc. Compared to physical corruption, the signs of failure are hardly detected and addressed due to its unpredictability. However, a minor problem can be a useful sign to suspect a leading logical corruption. Prevention from the corruption or Exchange database repair is impossible. The best you can do is regularly updating your Exchange Server for good because the latest version (Exchange Server v. 5.5) always comes with some fixes in bugs. Once you updated the pack, never change the configuration because manual configuration tends to create problems due to human errors. Always, and always, take error reports into account and check them. Use Isinteg for the Information Store error checking, and use Eseutil for the database engine.
A lot of things may happen and make you suffer from serious loss of important data. Thus, always perform online backup, not the offline one. Offline backup has great possibilities of human errors that can make things worse. A regular online backup is much better than an EDB repair.