NickName:Leonardo Ask DateTime:2013-06-05T03:32:08 Database mirroring a live database I've been reading about database mirroring on SQL Server 2008 R2 / 2012 and I have a question: does it matter if the database being mirrored is live? Do I have to do anything special or different if my database is live? EDIT-1: I have a (one) database on premises that's our production database. A few hundreds transactions happens per second, and 99.999% are read operations. Our plan is to mirror this database (single database) to SQL Azure (IaaS) as a "backup" structure, if the on premises environment crash for any reason, we just point to the cloud. I would like a zero loss, but I settle for a 5 seconds loss Latency wont be a problem... slow running is better than no running... I have just one node and one database Copyright Notice:Content Author:「Leonardo」,Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.Link to original article:https://stackoverflow.com/questions/16925971/database-mirroring-a-live-database Answers Chris H 2013-06-04T23:33:39 The biggest thing to consider if you run in either high-performance or high-safety mode.\n\nhttp://msdn.microsoft.com/en-us/library/ms189852.aspx\n\nBasically, in high-performance the transaction is committed locally and hopefully on the remote side. The mirrored server asynchronously applies the transactions and data loss may be a factor. The upside is not having latency in the local server and you only need two machines.\n\nIn high-safety, the transaction is witnessed by a third server and has to be committed on both sides. This creates latency which would not be desirable. ",