is High Availability something to describe Log Shipping and Always On ( replica )?
is Always on something to describe Log Shipping and High Availability?
I'm studying to get my certification 40-762 but I need to study a lot about these topics ( since i'm bad in this part on online tests ).
But even looking at Microsoft's website I'm confused about these topics. I know something about log shipping and replica, But I would like a point to study, and looking for "always on" and "high availability" not knowing what they are is a bit hard.
So, how can I describe them?
The AlwaysOn Availability Groups feature is a high-availability and
disaster-recovery solution that provides an enterprise-level
alternative to database mirroring. Introduced in SQL Server 2012,
AlwaysOn Availability Groups maximizes the availability of a set of
user databases for an enterprise. An availability group supports a
failover environment for a discrete set of user databases, known as
availability databases, that fail over together. An availability group
supports a set of read-write primary databases and one to eight sets
of corresponding secondary databases. Optionally, secondary databases
can be made available for read-only access and/or some backup
operations.
And does "availability groups" is when i have log shipping and replicas in the same server?
Best Answer
Always On is not synonymous with (Always On) Availability Groups and instead is more a marketing term to describe a suite of Microsoft High Availability technologies (which I argue is at best ambiguous). The term actually started out as "Always On" (note the space) a long time ago
as a pure marketing term (see my graphic as an example), but with the release of SQL Server 2012 was adopted as a wider catch all replacement marketing name for what they called "Hadron" during development (which was specifically Availability Groups) and several other HADR technologies (such as SQL Failover Clustering). The only difference was that when the term was first used, it did not have the trailing space (i.e. "AlwaysOn"). Marketing in their infinite wisdom have now added a space back into the term to add even more confusion :).
The bottom line is that if you completely ignore the use of the term AlwaysOn/ Always On and explicitly refer to the technology Availability Groups/ Failover Clustering/ Database Mirroring etc (or ask people to clarify which technology they are referring to) then you cannot go far wrong.