New features that have direct or indrect effects on increasing high availability for a SQL Server 2005-based implementation
- Increased number of nodes in a SQL cluster—You can create a SQL cluster of up
to eight nodes on Windows 2003 Data Center and up to four nodes on Windows
2003 Enterprise Edition. - Ability to do unattended cluster setup—Instead of having to use wizards to set up
SQL clustering, you can use the Unattended Cluster Setup mode. This is very useful
for fast re-creation or remote creation of SQL clustering configurations. - Full SQL Server 2005 services as cluster managed resources—All SQL Server 2005
services are cluster aware. - SQL Server 2005 database mirroring—Database mirroring essentially extends the
old log shipping feature of SQL Server 2000 and creates an automatic failover capability
to a “hot” standby server. (Chapter 16, “Database Mirroring,” covers database
mirroring in detail.) - SQL Server 2005 peer-to-peer replication—a new option of data replication that
uses a publisher-to-publisher model (hence peer-to-peer). - SQL Server 2005 fast recovery—Administrators can reconnect to a recovering database
after the transaction log has been rolled forward (and before the rollback
processing has finished). - Online restore—Database administrators can perform a restore operation while the
database is still online. - Online indexing—The online index option allows concurrent modifications
(updates, deletes, and inserts) to the underlying table or clustered index data and
any associated indexes during index creation time. - Database snapshot—SQL Server 2005 allows for the generation and use of a readonly,
stable view of a database. The database snapshot is created without the
overhead of creating a complete copy of the database or having completely redundant
storage. - Data partitioning improvements—Data partitioning has been enhanced with
native table and index partitioning, which essentially allow you to manage large
tables and indexes at a lower level of granularity.
- Addition of a snapshot isolation level—A new snapshot isolation (SI) level is being
provided at the database level. With SI, users can access the last committed row,
using a transactionally consistent view of the database. - Dedicated administrator connection—SQL Server 2005 introduces a dedicated
administrator connection that administrators can use to access a running server
even if the server is locked or otherwise unavailable. This capability enables administrators
to troubleshoot problems on a server by executing diagnostic functions or
Transact-SQL statements without having to take down the server.