Mecanismos de alta disponibilidad con Microsoft SQL Server 2008 Por: ISC Lenin López Fernández de Lara

Temario  Database Mirroring  Log Shipping  Replication  Failover Clustering  Demo

1.1 Database Mirroring Roles

1.2 Operating Modes High Availability High Safety High Performance

1.2.1 High Availability Operating Mode synchronous Automatic failover Writes a transaction to th transaction log The transaction is first committed on the mirror database Performance impact Uses simple ping

1.2.2 High Performance Operating Mode Asynchronous No automatic failover

1.2.3 High Safety Operating Mode Synchronous Manually failover Writes a transaction to th transaction log The transaction is first committed on the mirror database Performance impact

Log Shipping ¿What is?  Provides a means to maintain a secondary server on an automated basis using a chain of transaction log backups  Also allows you to configure a monitor server that can verify the health

1.1 Log Shipping Scenarios Offloading Report Activity Initialization for Database Mirroring Upgrading Versions or Migrating to a New Platform Primary or Secondary Availability Solution

1.1.1 Offloading Report Activity Reporting server SELECT statements Standby Mode

1.1.2 Initialization for Database Mirroring backups of the principal principal and mirror are synchronized minimizes the time

1.1.3 Upgrading Versions or Migrating to a New Platform build the new instance a brief outage on the applications move the databases

1.1.4 Primary or Secondary Availability Solution Secondary databases an outage of the primary database that applications can switch

1.2 Log Shipping Components

Replication ¿What is?  Replication is designed as a data-distribution mechanism.  The core replication engine is designed for very flexible implementation  The core architecture can be used to provide availability for a database because a redundant copy of data is maintained in synchronization with a master copy

1.1 Replication Components The basic building block of replication Can be defined against a table, view, stored procedure, or function Articles Publications are groupings of articles that define the replication set Publications You can apply one or more filters to each article that restrict the set of data that is replicated. You can fi lter articles by rows or by columns Filters

1.2 Replication Roles Maintains the master copy of the data within a replication architecture publisher Is the database that is receiving changes from the replication engine defined by the publication to which it is subscribing subscriber Is the main engine within a replication architecture The distribution database is stored on the instance that is configured as the distributor (An instance of SQL). distributor

1.3 Replication Topologies Central Publisher Other Central Subscriber

1.3.1 Central Publisher Topology

1.3.2 Central Subscriber Topology

1.6 Replication Methods Snapshot Replication Merge Replication Transactional Replication

1.6.1 Snapshot Replication 1. Snapshot Agent extracts the schema and BCPs the data 2. Distribution Agent then picks up and applies the snapshot to each subscriber (tables are dropped and re- created, then the data is copied using BCP) It is not normally used for high availability full replace of data

1.6.2 Transactional Replication  Begins with an initial snapshot being applied to the subscriber to ensure that the two databases are synchronized  As subsequent transactions are issued against the publisher, the replication engine applies them to the subscriber.

2.2 Transactional Options

Merge Replication ¿What is?  Merge replication is another alternative that can be applied to high-availability systems.  Merge replication was primarily designed for mobile, disconnected users.  By translation, the mechanisms are already built in for changes to occur at any location and get synchronized, as well as to be able to withstand failures and continue processing

3.1 Change Tracking (synchronize process) MSmerge _genhistor y MSmerge_to mbstone MSmerge _genhistor y MSmerge_to mbstone

Windows Clustering ¿What is?  Windows clustering enables multiple pieces of hardware to act as a single platform for running applications.

1.1 Windows Cluster Components

1.2 Types of Clusters Standard Windows Cluster Majority Node Set Cluster

2.2 Failover Cluster Instance Components The components that you need to configure for a SQL Server failover clustered instance are the following:  IP addresses  Network names  Disk drives on the shared drive array  SQL Server services  Service accounts

Demo  Mirroring High Availability

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