Sql server’s high availability technologies


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Sql server’s high availability technologies

  1. 1. SQL Server’s High Availability Technologies<br />
  2. 2. Technologies<br />Windows failover clustering <br /> provides protections against server failure.<br /><ul><li>Database mirroring and log shipping</li></ul> provide protection against site and database failure.<br />Peer-to-peer replication <br /> can provide protection against site and system failure.<br />Database snapshots<br /> provide protection against database corruption.<br />Fast recovery <br /> reduces the time required to recover a database from a backup.<br />
  3. 3. Failover clustering Overview<br />Server-level protection from both unplanned and planned downtime.<br />
  4. 4. Failover clustering<br />Multiple servers join together to form a cluster.<br />All of the nodes in a cluster are in a state of constant communication.<br />If one of the nodes in a cluster becomes unavailable, another node will automatically assume its duties.<br />
  5. 5. Database Mirroring<br />Database mirroring provides database-level protection from unplanned downtime<br />
  6. 6. Database Mirroring<br />Changes in the principal database are sent to a backup database called the mirrored database.<br />If the principal fails, the mirrored database on a different SQL instance will be instantly available.<br />Just protects user databases.<br />The transaction log is monitored for changes to the principal database.<br />changes are then copied out of the transaction log of the principal server and sent over the network to the mirror server.<br />
  7. 7. Log Shipping<br />An inexpensive protection against server failure.<br />
  8. 8. Log Shipping<br />Transaction log backups are periodically sent from the primary server’s database and applied to the database on the backup server.<br />Log shipping can send the captured transaction logs to multiple destinations.<br />All recovery for log shipping is manual. There is no automatic failover. <br />
  9. 9. Designed for bidirectional replication and high availability scenarios<br />Database changes can be made to any of the peer nodes, and each node publishes the updates to the other peer nodes.<br />Peer-to-Peer Replication<br />
  10. 10. Peer servers are continually available.<br />Can be used by applications or used as distributed reporting servers.<br />Does not offer any automatic failover<br />Peer-to-Peer Replication<br />
  11. 11. Enable databases to recover more quickly from unplanned downtime.<br />As changes are made to the database, the changed pages are copied into the snapshot<br />Restore the database by copying to it the original pages saved in the snapshot.<br />Database Snapshots<br />
  12. 12. Backup and restore process allows an entire database to be recovered to any given point in time.<br />Full backup A full database backup is a complete copy of the database. <br />Differential backup A differential backup copies only the database pages modified after the last full database backup.<br />Transaction log backup The transaction log backup copies the changes that have occurred since the last full or differential backup. <br />Transaction log backups may be applied after the last full or differential backup has been restored.<br />Backup and Restore<br />
  13. 13. Summary of SQL Server 2008’s High Availability Options<br />
  14. 14. Proposed Design<br />