Database Reference
In-Depth Information
them from the impact of noisy neighbors.
Table 6.4
outlines some of the key attributes of the storage controller options for your
SQL Server VMs.
Table 6.4
Supported Virtual Machine Storage IO Controllers
VMware's Paravirtualized SCSI controller (PVSCSI) is a high-performance SCSI
adapter that allows the lowest possible latency and highest throughput with the lowest
CPU overhead. In VMware vSphere 5.x, PVSCSI is the best choice, even if you don't
expect your database to be issuing large amounts of outstanding IO operations.
However, like SATA, PVSCSI can't be used with SQL Server AlwaysOn Failover
Cluster Instances, which leverage shared disk clustering. When you are using AlwaysOn
Failover Cluster Instances, your only option is LSI Logic SAS.
Caution
Changing the storage controller type after Windows is installed will make the
disk and any other devices connected to the adapter inaccessible. Before you
change the controller type or add a new controller, make sure that Windows
contains the necessary drivers. On Windows, the driver must be installed and
configured as the boot driver. Changing the storage controller type can leave your
virtual machine in an unbootable state, and it may not be possible to recover
without restoring from backup.
Choosing a virtual storage controller with a higher queue depth will allow SQL Server
to issue more IOs concurrently through Windows and to the underlying storage devices
(virtual disks). By having more virtual disks (more drives or mount points), you
increase the amount of queues that SQL Server has access to. Balancing the number of
data files to drive letters, to virtual disks, and to adapters allows you to maximize the
