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You would be hard-pressed to find an enterprise IT environment today that doesn't use virtual servers. The overall percentage of virtualized workloads in enterprise environments has risen dramatically over the last several years and the breadth of applications that are virtualized has expanded as well. While this has provided significant benefits -- increased server resource utilization, reduced costs, and improved manageability and resiliency of compute infrastructure, for example -- the storage side of the picture is often not as well developed.
Organizations need to understand that providing effective storage for virtual servers requires some different approaches in physical server environments. Storage protocols are one of the first options administrators should consider when determining a virtual machine (VM) storage approach.
Differences in storage protocols
Most virtual server technologies can use a range of protocols to connect the physical server running the VMs to the networked storage back end. Some may not have been viable with physical servers; block protocols such as Fibre Channel and iSCSI, and file protocols such as NFS and CIFS are options.
Fibre Channel is the most widely used storage networking protocol for virtual server environments due to its high performance and reliability for critical applications, and because it's generally the protocol that enterprise storage teams know best.
That said, Ethernet-based storage networking (iSCSI, NFS or CIFS) can reduce the cost and complexity of a virtual server environment by using cheaper, more common switches as well as what the larger network team already buys and manages rather than a separate network.
Storage protocol choices: How do I decide?
Your protocol selection will likely hinge on whose storage you use, the technologies your storage administration team is familiar with managing, and recommendations made by the storage vendors you have under consideration. Virtualizing servers could represent a good opportunity to consider a shift in storage networking strategy, allowing you to reduce cost and complexity while improving performance.
Consider these approaches when trying to finalize your storage protocol decision:
- The vendor-centric approach. Most vendors favor one protocol option. For example, VMware has said performance doesn't vary significantly from one protocol to another, provided each protocol is configured correctly and talks to sufficiently high-performance storage. EMC is fairly FC-centric, while the majority of NetApp customers use NFS for virtual server environments; however, both of these vendors offer options for all the supported protocols. Nimble Storage is an example of a company that decided to bet on the future by supporting iSCSI and not FC in its offering, which is frequently used for virtual server workloads.
- The cost-reduction approach. Performance doesn't vary much between protocols, so why not choose the option with the lowest total cost? In many cases, this means switching to Ethernet -- either iSCSI or NFS. Just be careful you configure it correctly.
- Go with what you know. Reducing islands of management helps, and avoiding the learning curve that comes with implementing new technology can be valuable. One approach is to avoid implementing technology your team isn't familiar with and stick with what you already use.
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