Microsoft is making huge investments in cloud technology and is betting big for future growth in this area. Microsoft has started providing cloud services for various products, applications, Operating System or hardware support. Based on the type of service, Microsoft has made available different offerings which include Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). Microsoft cloud support many applications or products out of which SQL Server is one of the Microsoft product which is supported on cloud by Microsoft. There are two different kind of offerings provided by Microsoft for SQL Server, which are Infrastructure as a Service (IaaS), Platform as a Service (PaaS).
Among these two services Infrastructure as a Service (IaaS), Platform as a Service (PaaS) offered by Microsoft, we a DBA or management, we need to understand what best suits our requirement and based on that we can choose the offering. It is important to understand the differences between these two offerings available for SQL Server, so that we can make an informed decision. Each offering for SQL Server from Microsoft has its own advantages and disadvantages interms if features, cost, High Availability, Disaster recovery, which operations tasks are taken care by Microsoft, etc. Below are some of the differences between SQL Azure SQL Database (PaaS) and SQL Server in Azure VM (IaaS).
SQL Azure database as service is best suited for new applications designed or optimized for cloud solutions or which depend on other cloud technologies, so that they can be used together. Developers building software-as-a-service (SaaS) applications can use Azure SQL Database to provide flexibility to support both explosive growth and profitable business models. On the other hand with Infrastructure as a Service (IaaS) is for applications which are already existing ones and cannot be changed easily and need to be migrated on to cloud without much changes to be made. Applications which are dependent on other on-premise resources are best suited for Infrastructure as a Service (IaaS) compared to SQL Azure database as service.
SQL Azure database as service does not support all features available in SQL Server and has many limitations for each feature, many of the features cannot be controlled by DBAs or developers and there is not much control for DBAs for operational tasks like patching, backups, HA or DR. Infrastructure as a Service (IaaS) is just like on-premise SQL Server instance on which DBAss or developers can make configuration changes, performs backups/restores, use required technologies for HA and DR purposes, etc. There are some limitations with SQL Azure database as service like max database size supported as of 2015 is only 500 GB, but this limitation does not apply for Infrastructure as a Service (IaaS). Another limitation include, SQL Azure database as service does not allow resources to be accessed from Azure to on-premise. Infrastructure as a Service (IaaS) does not have any such limitations.
In Infrastructure as a Service (IaaS), hardware, its maintenance costs are eliminated as it is taken care by Microsoft. SQL Azure database as service also eliminates the costs mentioned before, in addition to that, in SQL Azure database as service also eliminates maintenance and administration efforts and costs of patching, backups, HA, DR, etc. in SQL Azure database as service, there are different services available to choose for High Availability and disaster recovery where Point in Time Restore, Geo-Restore, and Geo-Replication to increase can be chosen to increase business continuity. In Infrastructure as a Service (IaaS), the High availability and disaster recovery is to be taken care by DBAs and we can choose any technology of our choice and we are responsible for administering, monitoring and fixing any problems.
Hope this was helpful.
This is applicable for below versions of SQL Server
SQL Server 2008 R2
SQL Server 2012
SQL Server 2014
SQL Server 2016
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