Availability Group - backup preferences.
1) what is the best practice standard, pros/cons of doing backups to primary vs (any) secondary?
2)would this be the same for both synch/asynch modes? (SQL 2012)
2)would this be the same for both synch/asynch modes? (SQL 2012)
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Here's a pretty good summary:
http://info.tricoresolutions.com/blog/understanding-backups-with-sql-server-alwayson-high-availability-mirrors
If you're doing synchronous mode, it makes sense to use the secondary node - it's always got the same data on it, so it allows you to offload the traffic of a backup to another server. There are some licensing concerns to be aware of if you're backing up a secondary node (you have to license it, where you normally don't have to license a non-active failover node in most cases), so do some reading.
If you're in asynchronous mode, it's a bit more nuanced - it really depends on how much data loss you can tolerate. If the async replica falls behind, you're taking a backup on out-of-date data - probably not by much time at all (just a few seconds, usually), but be sure you understand the replication latency before making that decision. If you want the most up to date data in your backup, you either need to backup the primary node or a synchronous replica.
http://info.tricoresolutions.com/blog/understanding-backups-with-sql-server-alwayson-high-availability-mirrors
If you're doing synchronous mode, it makes sense to use the secondary node - it's always got the same data on it, so it allows you to offload the traffic of a backup to another server. There are some licensing concerns to be aware of if you're backing up a secondary node (you have to license it, where you normally don't have to license a non-active failover node in most cases), so do some reading.
If you're in asynchronous mode, it's a bit more nuanced - it really depends on how much data loss you can tolerate. If the async replica falls behind, you're taking a backup on out-of-date data - probably not by much time at all (just a few seconds, usually), but be sure you understand the replication latency before making that decision. If you want the most up to date data in your backup, you either need to backup the primary node or a synchronous replica.
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