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David Barbarin

Weird issue with sys.fn_hadr_backup_is_preferred_replica() function

By | Hardware & Storage | No Comments

A couple of days ago, I faced a weird backup issue with SQL Server AlwaysOn and availability groups at one of my customer (thank to him to point out this issue ). After installing our DMK tool (Database Management Kit) about database maintenance for AlwaysOn, my customer noticed that their databases have not backed up. Ouch … what’s going on? I never ran into this issue before… Do the problem comes from our tool? In…

 
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David Barbarin

SQL Server 2014: FCIs, availability groups, and TCP port conflict issues

By | Operation systems | One Comment

After giving my session about SQL Server AlwaysOn and availability groups at the last French event “Les journées SQL Server 2014”, I had several questions concerning the port conflict issues, particularly the differences that exist between FCIs and availability groups (AAGs) on this subject. In fact, in both cases, we may have port conflicts depending on which components that are installed on each cluster node. Fundamentally, FCIs and AAGs are both clustered-based features but each…

 
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David Barbarin

SQL Server: Forced failover with AlwaysOn & Availability Groups

By | Hardware & Storage | No Comments

During a workshop at one of my customer about the implementation of SQL Server AlwaysOn and availability groups, I had an interesting discussion. It was about asynchronous replication between 2 replicas and the effect of the forced failover operation with allowed data loss. Does SQL Server resynchronize availability databases if I loose some transactions during the failover process? The quick answer is yes but probably the most interesting question is how SQL Server achieves resynchronization…

 
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