Information Technology Reference
In-Depth Information
Your storage vendor's best practices/solutions guides
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Sometimes the documents go out of date. Don't just ignore the guidance if you think it's
incorrect; use the online community or reach out to VMware or your storage vendor to get the
latest information.
Most important, have no fear!
Physical host and storage coni gurations have historically been extremely static, and the pen-
alty of error in storage coni guration from a performance or capacity standpoint was steep. The
errors of misconi guration would inevitably lead not only to application issues but to complex
work and downtime to resolve. This pain of error has ingrained in administrators a tendency to
overplan when it comes to performance and capacity.
Between the capabilities of modern arrays to modify many storage attributes dynamically
and Storage vMotion (the ultimate “get out of jail free card”—including complete array replace-
ment!), the penalty and risk are less about misconi guration, and now the risk is more about
oversizing or overbuying. You cannot be trapped with an underperforming coni guration you
can't change nondisruptively.
More important than any storage coni guration or feature per se is to design a highly avail-
able coni guration that meets your immediate needs and is as l exible to change as VMware
makes the rest of the IT stack.
h
e Bottom Line
Differentiate and understand the fundamentals of shared storage, including SANs and
NAS.
vSphere depends on shared storage for advanced functions, cluster-wide availability,
and the aggregate performance of all the VMs in a cluster. Designing a high-performance
and highly available shared storage infrastructure is possible on Fibre Channel, FCoE, and
iSCSI SANs and is possible using NAS; in addition, it's available for midrange to enterprise
storage architectures. Always design the storage architecture to meet the performance
requirements i rst, and then ensure that capacity requirements are met as a corollary.
Master It
Identify examples where each of the protocol choices would be ideal for dif-
ferent vSphere deployments.
Master It
Identify the three storage performance parameters and the primary de-
terminant of storage performance and how to quickly estimate it for a given storage
coni guration.
Understand vSphere storage options.
vSphere has three fundamental storage presentation
models: VMFS on block, RDM, and NFS. The most l exible coni gurations use all three, pre-
dominantly via a shared-container model and selective use of RDMs.
Master It
Characterize use cases for VMFS datastores, NFS datastores, and RDMs.
Master It
If you're using VMFS and there's one performance metric to track, what
would it be? Coni gure a monitor for that metric.
Coni gure storage at the vSphere layer.
After a shared storage platform is selected,
vSphere needs a storage network coni gured. The network (whether Fibre Channel or
Ethernet based) must be designed to meet availability and throughput requirements, which
are inl uenced by protocol choice and vSphere fundamental storage stack (and in the case of
NFS, the network stack) architecture. Proper network design involves physical redundancy
and physical or logical isolation mechanisms (SAN zoning and network VLANs). With