Database Reference
In-Depth Information
Linux). Note that this is the native operating system, not a guest operating system. On top
of the native operating system, you could have both applications running on the native
operating system itself and a Type-2 hypervisor also running. Then running on the Type-
2 hypervisor could be one or more virtual machines and their various guest operating
systems.
Drawbacks to the Type-2 Hypervisor
If the operating system sitting on the hardware crashes, it will bring everything down on
the box, including the Type-2 hypervisor. If a hacker breaches the operating systems on
which the Type-2 hypervisor is running, then everything is at risk. This makes the Type-
2 hypervisor only as secure as the underlying operating system on which it is running. If
critical security patches are released for that operating system that have nothing to do
with virtualization, you are now required to patch those boxes and work these patches in
with your patching of the guest operating systems. In our opinion, serious virtualization
requires a Type-1 hypervisor at a minimum.
Paravirtual SCSI Driver (PVSCSI) and VMXNET3
PVSCSI is a great driver to use for all your I/O-intensive virtual machines. we can't
think of a more I/O-intensive VM than a SQL Server database. Based on our experience,
you will see a 10%-12% improvement in I/O throughput. You will also experience up
to a 30% reduction in CPU usage.
This driver is best suited for all your I/O-intensive workloads, especially a SAN
environment. It is not well suited for direct attached storage. In order to use this driver,
you will have to have the VMware tools installed on the VM.
Bottom line: You will have much lower latency to the underlying storage layer and
much lower CPU consumption. This is a win-win situation. This is very useful with an
I/O-intensive application such as a SQL Server database on a virtualized infrastructure.
Chapter 6
,
“
Architecting for Performance: Storage
,
” will go into great detail about the
underlying storage layer.
VMXNET3 is the third-generation paravirtualized NIC designed for network
performance. Think of VMXNET3 as a network adapter that is optimized for network
performance in a virtualized infrastructure. The key point is that the OS does not get
altered in any way in order for VMXNET3 to be able to enhance network performance.
Installation Guidelines for a Virtualized Database
A common question that's asked is, “When installing my virtualized SQL Server
database, what installation guidelines should I follow?” The answer is quite simple: the
same installation guidelines you have always followed. The same as you would on a
physical environment. A virtualized database running on vSphere behaves exactly like a
