Database Reference
In-Depth Information
about using SQL Server 2012 Column Storage with SAP BW, refer to
Database Availability Design Impacts on Storage Performance
The database availability design you choose will have a direct impact on your storage
performance. The choice between the different availability types varies. In this topic,
we are focusing mainly on standalone instances using VMware vSphere HA, SQL
Server 2012 AlwaysOn Availability Groups (AAG), and AlwaysOn Failover Cluster
Instances (FCIs). Standalone instances and FCI have relatively the same storage
capacity requirements (unless local Temp DB is used in the FCI case) and have the
same storage performance requirements. AlwaysOn Availability Groups, which has
some advantages from an availability and data protection standpoint, at least doubles
the total capacity requirements as well as adds additional IO overhead, dependent on
the workload, and specifies how many inserts, updates, and deletes there are, as each
database change must be replicated.
Tip
No matter which availability choice you make, you need to plan for the storage
performance and capacity requirements of that choice. We will cover the details
of SQL Server availability design, including AlwaysOn Availability Groups and
Failover Cluster Instances, in
Chapter 9
.
Volume Managers and Storage Spaces
When you set up storage within Windows, you have the option of using the Windows
Volume Manager with Basic or Dynamic Disks or using Storage Spaces (Windows
2012 onwards). Dynamic Disks and Storage Spaces provide options that include
spanning volumes, striping volumes, and fault-tolerant volumes inside the guest
operating system. Managing spanned, striped, or fault-tolerant volumes inside Windows
adds an unnecessary IO overhead when you are virtualizing your SQL Server—
especially as you are being provided with these services through your underlying
storage devices and your virtual disks can be expanded online without disruption.
Because of the way that SQL Server manages its data files, and effectively accesses
them and stripes the files anyway, there is no need to add any additional layers of
striping for performance inside Windows. We recommend the use of basic disks in
Windows and the GPT (GUID Partition Table) partition format for all SQL Server
partitions. Using GPT, you will be able to expand the partitions beyond 2TB in the
future (vSphere 5.5 or above required) if the need arises. As a best practice, you should
