CHAPTER 3 n RESTORING A DATABASE 45
Availability During Recovery
Normally, as a database is recovering, it remains unavailable to users. With SQL Server
2005 Enterprise Edition, a database is made available immediately after committed
transactions are rolled forward. This process is illustrated in Figure 3-2. The database is
available online to users, while the rollback process proceeds. This might seem like trivial
functionality, but imagine the case of the massive delete; rolling back millions of rows
could mean hours, depending on the hardware involved.
Figure 3-2. After committed transactions in the log file are rolled forward, the database is
online, but only when using fast recovery in SQL Server 2005 Enterprise Edition. If fast
recovery isn??™t available, you may be waiting awhile while the database finishes the
complete process of recovery.
By making the database available immediately after the roll-forward process, you
can increase the uptime significantly in the event of some sort of disaster. The rollforward
process is usually quite fast.
Periodically, the database forces committed transactions to be written to the database.
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