SQL SERVER 2008 Database engine details _mssql2008

The database Engine component of SQL Server is a core service for storing, processing, and guaranteeing data security. The database engine provides controlled access and fast transaction processing to meet the requirements of an enterprise that requires extremely high data usage.
SQL Server supports up to 50 instances of the database engine on the same machine. For local installations, you must run Setup as an administrator. If you install SQL Server from a remote share, you must use a domain account that has read and execute permissions on the remote share.

Overview of High availability Solutions
High availability solutions reduce the impact of hardware or software failures, maintain application availability, and minimize the downtime that users feel.
• Failover Clustering
A failover cluster consists of one or more nodes or servers that have two or more shared disks. The SQL Server failover cluster instance will appear as a single computer on the network, but it has the ability to failover between nodes if the current node is unavailable. For example, in the event of a non-disk hardware failure, operating system failure, or planned operating system upgrade, you can configure an instance of SQL Server on one node of a failover cluster to fail over to any other node in the disk group.
L Database Mirroring
Database mirroring is actually a software solution that provides an almost instantaneous failover to improve database availability. Database mirroring can be used to maintain a single standby database (or "mirrored database") for a corresponding production database, called the principal database.
l Log Shipping
As with database mirroring, log shipping is a database-level operation. You can use log shipping to maintain one or more warm standby databases for a corresponding production database, called the primary database. The standby database is also known as a secondary database. Create each secondary database by restoring or using a backup of the database that does not restore the primary database. Using Backup restore, you can use the generated secondary database for a limited report.
l Replication
Replication uses publish-subscribe mode. This allows the primary server (called the publisher) to distribute data to one or more secondary servers, the subscribers. Replication provides real-time availability and scalability between these servers. It supports filtering to provide a subset of data to subscribers and also supports zoning updates. The Subscriber is online and can be used for reporting or other functions without query recovery. SQL Server provides three types of replication: snapshot replication, transactional replication, and merge replication. Transactional replication has the shortest latency and is often used in situations where high availability is required.
• Scalable shared database
You can use the scalable shared database feature to extend a read-only database that is specifically generated for a report. The report database must reside on a set of dedicated, read-only volumes that are used primarily to host the database. With commercial server hardware and commercial volume hardware, you can extend the reporting database to provide the same view of report data on multiple report servers. This feature also allows the report database to use a smooth update path.