Information Technology Reference
In-Depth Information
you assign a vSphere DRS automation level to the primary VM (the secondary VM assumes the
same setting as the primary VM).
Without EVC, vSphere DRS is set to Disabled for the fault-tolerant VMs, initial placement is
provided only for the secondary VM, and neither of the fault-tolerant VMs is included in cluster
rebalancing calculations or operations.
Examining vSphere Fault Tolerance Use Cases
vSphere FT is not designed or meant to be run on all your VMs. You should use this service
sparingly and take this form of fault tolerance only for your most important VMs. The docu-
mentation for VMware's coni guration maximums states that there should be no more than
four vSphere FT-protected VMs (primary or secondary) on any single ESXi host. Remember,
once you have primary and secondary VMs locked and in sync, you will be using double the
resources for a protected VM.
Now that we have looked at a couple of high-availability options, let's move on to planning
and designing for disaster recovery.
Planning for Business Continuity
High availability is only part of the solution, one component in the bigger picture of business
continuity. Business continuity is about ensuring that the business can continue operating in
the face of some signii cant event. High availability deals with business continuity from a fairly
narrow perspective: ensuring that the business can continue operating in the event of a physi-
cal server failure, an OS or application failure, or a network component failure. There are many
more types of failures that you must account for and protect against, but we'll mention two pri-
mary ones here:
First, you'll need to protect against the loss of data due to equipment failure, software mal-
function, or simple user error (ever deleted something by mistake?).
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Second, you'll want to ensure that you've done the necessary work around plan ning for
disaster recovery in the event your entire datacenter is rendered unusable or unavailable.
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Most organizations have a policy or a set of policies that dei ne the processes, procedures,
tools, and technologies that help address these failure scenarios. As you review the information
provided in the following sections, you'll want to be sure that any solution you are considering
complies with your company's policy for business continuity. If your company doesn't yet have
a policy for business continuity, now is a great time to create one!
In the next two sections, we'll look at both of these failure scenarios, along with some of the
products and technologies that are applicable. Let's start with data protection.
Providing Data Protection
Backups are an essential part of every IT department's responsibilities, yet they're often the
source of the greatest conl ict and frustration. Many organizations hoped that virtualizing
would make backups easier, and in some ways it has. In other ways, it has made backups more
difi cult as well. We'll examine the basic methods for backing up VMs and then provide an over-
view of VMware Data Recovery, a backup solution provided by VMware to help with smaller
implementations of vSphere.
