Monday, December 29, 2008

Interview Question - DB Mirroring vs Clustering


Database mirroring and Clustering – both can serve the purpose of high availability and data protection. However Database mirroring is at database level only. Clustering is at server level, all databases on the instance are covered. In case of clustering there is a single copy of your data and log files where in case of mirroring you have multiple copies of files – on primary and secondary server both,  which increases your chances of recovery in case of disaster. In case of mirroring you cannot mirror the system databases viz. master, msdb etc. For mirroring to work database recovery model has to be set to "full recovery". I would see mirroring as a sophisticated log shipping mechanism with automatic failover capability.


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About Me

By profession I am a Database Administrator (DBA) with total 13 yrs. of experience in the field of Information Technology, out of that 9 yrs as SQL DBA and last 3 years in IBM System i/iSeries and DB2 LUW 9. I have handled Developer, plus production support roles, and I like both the roles. I love and live information technology hence the name "Techonologyyogi" Apart from that I am a small, retail investor, with small investments in India and United States in the form of Equity holdings via common stocks. Don't ask me if I have made money, I have been loosing money in stocks.