HP 3PAR Application Software Suite for Microsoft Exchange - Manual (Page 92)

8.2 Key Microsoft Exchange File Types
3PAR Recovery Manager 4.1.0 For Microsoft Exchange 2010 User’s Guide
8.1 Key Microsoft Exchange File Types
Before discussing backup and recovery for Microsoft Exchange, it is important to understand
the elements of Exchange.
The Microsoft Exchange Mailbox Database uses three key file types for all operations:
■ Log file (*.LOG). A file in which transaction log records are stored.
■ Checkpoint file (*.CHK). Maintains information about the location in the transaction logs
that was last committed to the database.
■ Database file (*.EDB). Properties data file to store all user data.
LOG files are accessed in a sequential order; EDB files are accessed with random I/O patterns.
For optimal performance and to facilitate database management, transaction logs should be
placed on a volume that performs sequential I/O in an optimal manner such as a RAID 1
volume. The EDB files should be placed on a separate volume that is optimized for random I/O
such as a RAID 5 volume. For additional information on creating volumes, see the 3PAR InForm
OS CLI Administrator’s Manual.
From the performance and management point of view, a dedicated volume should be created
for every log file group on each Mailbox Dtaabase and another data volume should be created
for EDB files for each data store on every Mailbox Database. For example, if you have two
storage groups, each with a log and five mailbox stores, create two RAID 1 volumes for the
logs, and ten RAID 5 volumes for the EDB files.
When a change is made to the Mailbox Database, Exchange updates the data in the memory
(32K pages) and synchronously writes a record of the transaction to the log in sequential order.
This record allows Exchange to re-create the transaction in the event of a failure. The database
engine then writes the data to the disk in large I/O operations. Exchange supports circular
logging to save disk space on the volume containing log files. However, circular logging makes
hard recovery (restoring from backup) impossible. It is recommended that the circular logging
feature be disabled. Circular logging is disabled by default in Microsoft Exchange.
8.2 Backup
An online backup of Exchange runs while the data store is mounted. A full backup backs up
the entire information store and transaction log. It also truncates the log after the log has
been backed up to reduce disk space usage.