Exchange Server 2010 Database (part 1)

When the Exchange Database will be deployed, we have to know it have some significant change in the database architecture of Exchange Server 2010.
   ● Storage Group no longer exist --- that is the storage group integrates into the Exchange database.
   ● Database are no longer child objects of Exchange Mailbox servers --- that is database will be configured at the organizational level now.
   ● All databases require the unique names within an organization

Before configure Exchange database, we need to know the database description or conception.
   ● Mailboxes and public folders store in Exchange databases
   ● Mailbox servers can contain both public folder and mailbox database
   ● Each database has a single set of transaction logs --- that is each database have its own set of transaction logs
   ● Transaction logs record changes as messages sent to or from the database
   ● Each individual database and its transaction logs are stored in the same folder by default --- that is a single folder by default holds a database and its transaction logs
   ● The location of a database and its transaction logs is the different with other one
  
In this folder locates database and its transaction logs, there is some types of files and its function is as follows:
   ● Checkpoint file (.chk)   ---> Determine which transactions in the current transaction log need to be committed to the database
   ● Current transaction log file (exx.log)   ---> Express which transactions are written
      If this file size reach 1 MB,Exchange Server 2010 close this log file next to rename it, and create a new current transaction log file.
   ● Closed transaction log file (.log)   ---> When a current transaction log size reaches 1 MB, it will be rename to Closed transaction log file and has a longer file name.
   ● Reversed transaction log file (.jrs)   ---> Play a emergency storage if the disk become full and a new transaction log cannot be created
      When the database take offline, any transactions cannot write into the current transaction log so that write to a reserved transaction log file that each file size is 1 MB.
   ● Temporary workspace file (<log prefix>tmp.log)   ---> It just only for the temporary workspace and its size cannot exceed 1 MB
   ● Exchange database file (.edb)   ---> Store content for mailbox and public folder database and the size limit is 64 TB

And the above file number as Closed transaction log will depend on whether circular logging is enabled or disabled. Although you can enable circular logging to limit storage capacity, Microsoft still recommends that Exchange Server 2010 databases not be configured to use circular logging if we will plan to use the Volume Shadow Copy Service to enable third-party backup & restore operations.

If circular logging is enabled, we need to notice
   ● When database is restored, the transaction logs in the same directory maybe deleted and only point-in-time recovery operation is possible.
   ● Incremental and differential backup operation is not permitted
   ● The restoration of individual databases will be prohibited if perform a backup or recovery operation