Exchange Server 2010: Deploying Exchange Databases (part 1) - Configuring Exchange Databases

1. Configuring Exchange Databases

Exchange Server 2010 stores mailboxes and public folders in Exchange databases. Mailbox servers can contain both public folder and mailbox databases. Each database is stored in a single Extensible Storage Engine database (.edb) file. The database file in which a particular message is stored does not change, regardless of the type of client that sends or reads the message.

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CREATING AND CONFIGURING EXCHANGE DATABASES

You must be assigned the Organization Management role to enable you to create and manage mailbox or public folder databases on any Mailbox server or the Server Management role to create databases on a specific server in an Exchange organization. Users assigned the View Only Organization Management role can view database properties but cannot modify any of those properties.

Each database has a single set of transaction logs that record changes to the database, including messages sent to or from the database. Transaction logs can be used in disaster recovery scenarios if high-availability features are not implemented. However, their primary function is to ensure that Exchange Server 2010 follows the Atomicity, Consistency, Isolation, and Durability model for databases. Each individual database and its transaction logs are by default stored in the same folder but in a different folder from all other databases. By default, the folders that hold the databases are stored in the folder path C:\Program Files\Microsoft\Exchange\Server\v14\Mailbox, as shown in Figure 1.

A single folder by default holds both the database and its transaction logs. You should, however, consider storing transaction logs in separate folders and on a different hard disk from the databases. Because transaction logs can be used in disaster recovery in situations where high-availability solutions are not implemented, you might be unable to restore to the point of failure if you lose both the database and its transaction logs in the same disk crash.

Note:

Exchange Server 2000 and Exchange Server 2003 enabled multiple databases to share a single set of transaction logs through the use of storage groups. Exchange Server 2007 also offered this functionality but only for databases that did not have high-availability features enabled. In Exchange Server 2010, each database must have its own set of transaction logs. If you see an answer in the 70-662 examination that proposes shared transaction logs or a storage group, then you can reject this answer.

The folder that contains an Exchange database (.edb) file can also contain other types of files. Figure 2 shows the files in a public folder database folder. The possible file types in an Exchange database folder are as follows:

• Checkpoint file (.chk) Determines which transactions in the current transaction log need to be committed to the database.

• Current transaction log file (exx.log) The file into which new transactions are written. When this file reaches its storage limit of 1 megabyte (MB), Exchange Server 2010 closes the log file, renames it, and creates a new current transaction log file.

• Closed transaction log file (.log) Closed transaction log files have the same file type (.log) as the current transaction file but have a longer file name. For example, a current transaction file E00.log might be named E000000000001.log when its size reaches 1 MB.

• Reserved transaction log files (.jrs) Exchange Server 2010 uses these files as emergency storage when the disk becomes full and it cannot create a new transaction log. The database is taken offline, and any transactions that cannot be written to the current log are written to a reserved transaction log file. Reserved transaction log files are 1 MB in size.

• Temporary workspace file (<log prefix>tmp.log) The transaction log file for the temporary workspace (for example, E00tmp.log). The size of this file cannot exceed 1 MB.

• Exchange database file (.edb) Stores content for mailbox and public folder databases. The size limit for this type of file is 64 terabytes (TB), although in practice a lower size limit will probably be imposed by disk size restrictions.

Detailed instructions for configuring a mailbox database are given later in this lesson. However, for high-level configuration of database options in the EMC, click Mailbox under Organization Configuration and select the Database Management tab, as shown in Figure 3. Right-click the database you want to configure and click Properties. This accesses the General, Maintenance, Limits, and Client Settings tabs.

The General tab gives information about the database, such as its backup status, when it was last modified, the server on which it is mounted, the path to the database file, and servers that have a copy of the database.

On the Client Settings tab, you can specify the default public folder database and, if appropriate, the default offline address book for all mailboxes in a database.

The Limits tab, shown in Figure 4, lets you specify the storage limits for the database, at what database size a warning is issued, and the database file sizes at which Send and Send and Receive are prohibited. You can configure the notification schedule for sending messages to users who have exceeded these limits. The tab permits you to specify deletion settings that determine how long the database retains mailboxes and deleted items within mailboxes after a user deletes them.

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RECOVERABLE ITEMS AND THE DUMPSTER

For more information about recoverable items and single item recovery, access http://technet.microsoft.com/en-us/library/ee364754.aspx and follow the links.