Exchange backup and recovery concepts

*** Exchange store consists of edb and stm database files. edb contains rich text content, while stm is used to store content for non-MAPI compliant mail clients. Each storage group shares transaction, checkpoint and temporary log files

*** Transaction log files are 5 MB in size and are automatically rotated by exchange once they hit that size limit. Exchange will dismount the store, in case the threshold of total number of these files is exceeded. Backup programs including ntbackup therefore remove files files after performing a successful backup. Checkpoint files are 8 KB in size and keep track of the transactions already applied by exchange from the transaction files. Checkpoint file is helpful in recovering exchange as it does not have to apply all transactions or search for transactions that need to be applied after a disaster. Temporary log files are created for temporary storage.

*** ESEutil is used to repair exchange database files. Database files are in ESE format.

*** Exchange 2003 has recovery storage groups that allow to restore store backups to these groups and merged with original store without un-mounting the store. However, this feature is primarily used for individual mailbox recovery instead of a system disaster.