SQL Server high availability

Database mirroring, replication, failover clustering, log shipping, scalable shared databases. All these are good solutions for SQL Server high availability, which give easy and smooth work with SQL database. 

Database mirroring is a method for SQL Server high availability which make a snapshot of the database so when eventual problem occurs it is easy to restore the data. However, this solution can not restore all the data. The information written between the last snapshot and the failure will be lost. There some solutions that can help with that too. One of them is to involve a third server instance. This instance is also known as a witness.

Replication method for SQL Server high availability works really easy. You have a SQL database which you work with. There is another SQL database often named as a subscriber where the data you enter is replicated. So, in a case of a failure you will use the replicator to restore the data. 

Failover clustering is the most common method for SQL Server high availability. When you have failover clustering you have two or more nodes or servers which work together so when a problem happen the problem server is changed by the healty one. 

Except these three for SQL Server high availability you can also use methods like log shipping and scalable shared databases

SQL server scalability

The ability of each SQL infrastructure to accept additional information for a specified period of time exceeding the preset information system capabilities or said with other words – SQL server scalability  is one of the most important elements which every SQL infrastructure must possess to meet customer requirements.

The key factor when we have SQL server scalability is the need of preventing of data lost when a failure occur. The other important thing is the work of the user to continue smoothly, even if it is possible not be noticed that there is a problem.

There are several different approaches for SQL server scalability. The most common approach is so called partitioning. In that way the database is devided to many different servers combined in a cluster. When a server broke down the other servers continue to work so the broken one is not slowing down the whole work.
 
SQL server scalability is getting more and more important today when the whole amount of data that is being used is growing unstoppable and the challenges for the SQL workloads is getting bigger and bigger. Almost every day the amount of data imported in a database is  exceeding the preset information system capabilities and the need of SQL server scalability is clear. 

Virtualization of SQL server databases

The Enterprise protects, simplifies and consolidates databases by using SQL server virtualization. By consolidating the storage environment, developing the use and simplifying the operation and security of these reserves. Thanks to their improved SQL server virtualization  The Enterprise offers also the so called resource governor ability for storage which allows QoS management for each individual workload.