Database Reference
In-Depth Information
SE, Bob, came on site and we updated ESX (long live the MUI!) to the
appropriate version and we tested vMotion. I was sure it was a trick. I watched
as a nonbuffered video played in a virtual machine and was migrated from
ESX01 to ESX02. In fact, I was so sure it was a trick, I shut down ESX01. I
cannot recall the video that was playing, but I do recall that moment in time. What
was yours?
vMotion migrates the entire state of a virtual machine from one physical host to another
physical host. State information includes current memory content, BIOS, devices
attached to the virtual machine, CPU, MAC address, and other properties that make up
the virtual machine.
For your standalone SQL Servers, the value this brings is if there is an issue with the
underlying hardware (for example, the NIC goes bad) in a virtual environment, the SQL
Server virtual machine network traffic is seamlessly routed out another physical NIC
and the SQL Server VM can then be vMotioned to another physical host. There is no
downtime incurred by SQL to fix the failed NIC. From an SLA perspective, SQL
continues to provide services. In the physical world, you will have to shut down the
SQL Server, replace the NIC, and then power on the SQL Server. This is a service
interruption, or this means you are staying around to fix the NIC and ensure SQL boots
and resumes services during a change window. I know which option I like better:
vMotion the SQL Server, and let someone on the infrastructure team deal with the failed
NIC. vMotion is a battle-tested, tried-and-true core feature of the vSphere platform;
there is no reason not to use it (unless you are running SQL Server AlwaysOn Failover
Cluster Instances—more on that later).
Distributed Resource Scheduler (DRS)
DRS leverages vMotion technology to balance virtual machine workloads across
multiple ESXi hosts in a cluster. DRS pools the physical CPU and memory resources of
an ESXi cluster together and uses this aggregate information to make decisions on
where to best run the virtual machine workloads within the cluster; for a virtual SQL
Server, this is important. Some SQL Servers may sit dormant for two and a half months
but then, at the end of every quarter, will ramp up and consume all the resources
assigned to them. As these SQL Servers ramp up, DRS will move other virtual
machines that may conflict with CPU and memory resources off the ESXi host to another
ESXi host, thus freeing up the necessary CPU and memory resources for the SQL Server
requiring those resources.
Storage vMotion
Storage vMotion allows an administrator to migrate the storage of a virtual machine
