Exam 70-458 – Objective 3 – Implement high availability

This entry is part 3 of 8 in the series Exam 70-458

 

Implement AlwaysOn

 

Implement database mirroring (http://technet.microsoft.com/en-us/library/ms189852.aspx)

 

Implement replication (http://technet.microsoft.com/en-us/library/ms151198.aspx)

  • Troubleshoot replication problems (http://technet.microsoft.com/en-us/library/ms151756(v=sql.105).aspx)
  • Identify appropriate replication strategy (http://technet.microsoft.com/en-us/library/ms152531.aspx)
    • Snapshot –  when data changes are substantial but infrequent (http://technet.microsoft.com/en-us/library/ms151832.aspx)
      • Data changes infrequently.
      • Replicating small volumes of data.
      • A large volume of changes occurs over a short period of time.
    • Transactional (http://technet.microsoft.com/en-us/library/ms151176.aspx)
      • You want incremental changes to be propagated to Subscribers as they occur.
      • The application requires low latency between the time changes are made at the Publisher and the changes arrive at the Subscriber.
      • The application requires access to intermediate data states. For example, if a row changes five times, transactional replication allows an application to respond to each change (such as firing a trigger), not simply the net data change to the row.
      • The Publisher has a very high volume of insert, update, and delete activity.
      • The Publisher or Subscriber is a non-SQL Server database, such as Oracle.
    • Peer-to-peer (http://technet.microsoft.com/en-us/library/ms151196.aspx)
      • Catalog queries and other reads are spread across multiple nodes. This enables performance to remain consistent as reads increase.
      • If one of the nodes in the system fails, an application layer can redirect the writes for that node to another node. This maintains availability.
      • If a node requires maintenance or the whole system requires an upgrade, each node can be taken offline and added back to the system without affecting the availability of the application.
    • Merge (http://technet.microsoft.com/en-us/library/ms152746.aspx)
      • Multiple Subscribers might update the same data at various times and propagate those changes to the Publisher and to other Subscribers.
      • Subscribers need to receive data, make changes offline, and later synchronize changes with the Publisher and other Subscribers.
      • Each Subscriber requires a different partition of data.
      • Conflicts might occur and, when they do, you need the ability to detect and resolve them.
      • The application requires net data change rather than access to intermediate data states. For example, if a row changes five times at a Subscriber before it synchronizes with a Publisher, the row will change only once at the Publisher to reflect the net data change (that is, the fifth value).

 

Preparation resources

 

Click here to go back to main page for exam 70-458.

Series Navigation<< Exam 70-458 – Objective 2 – Implement SecurityExam 70-458 – Objective 4 – Design and implement a data warehouse >>
Tracy Boggiano
Follow me

Tracy Boggiano

Database Administrator at ChannelAdvisor
Tracy has spent over 20 years in IT and has been using SQL Server since 1999 and is currently certified as a MCSE Data Platform. She has worked on SQL Server 6.5 and up including currently SQL 2017 CTP 2.0. She enjoys monitoring, performance tuning, and disaster recovery technologies.

She also tinkered with databases in middle school to keep her baseball card collection organized.

Her passion outside of SQL Server is volunteering with foster children as their advocate in court through http://www.casaforchildren.org.
Tracy Boggiano
Follow me