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With server virtualization proliferating, most companies are hooking those virtualized environments into Fibre Channel SANs; but is that the best choice?
We did research over the last 18 months asking IT professionals about their major priorities and all of them emphatically stated that implementing VMware was one of their top initiatives to significantly drive down costs and improve operations. But these IT professionals also said the biggest challenge they face with their VMware environments is networked storage. With dedicated data storage managers buried under a mountain of projects and daily operations that consume so much of their time, taking on new tasks is nearly impossible.
Another important dynamic we've observed is that VMware administrators find themselves becoming quasi-storage administrators, which is somewhat akin to asking a brain surgeon to operate on someone's heart. This isn't due simply to the inherent complexity of most networked storage systems; it's an issue of specialization as well.
Ironically NFS, the protocol of geeks, is a means of simplifying VMware and networked storage. It turns out there are a number of shops using NFS with VMware and, as a result, they've eliminated much of the day-to-day complexity of managing network storage with VMware. Here are some of the advantages of using NFS with VMware rather than Fibre Channel (FC) or iSCSI SANs:
- very simple to add NFS datastores. With NFS there's no LUN management. This simplicity addresses configuration issues that might come back to bite you in a SAN environment. The storage provisioning process for SANs often requires a dozen or more time-consuming steps. Missing any one step may result in disaster and you might not know about it until it happens.
- You don't have to deal with all of the complexity of Fibre Channel, WWNs, zones, ISLs, etc.
- You can easily increase -- or more importantly -- decrease the size of NFS datastores online for capacity reclamation.
- Because you're using NFS, you don't have to deal with VMFS or raw device mappings (RDMs). This means you can have volumes bigger than 2 TB. NetApp supports a 16 TB file system, and Isilon Systems and BlueArc can support hundreds of terabytes in a datastore (and, theoretically, even more).
- There's no single disk I/O queue with NFS, which means performance is dependent on network bandwidth and the data storage system itself. It also means NFS performance can even keep up with Fibre Channel in VMware environments.
- You can back up whole virtual machines (VMs) or files within VMs.
- Restoration of VMs is flexible, including individual VMs, multiple VMs or files within VMs.
- The cost of Fibre Channel is higher, including the equipment and support. This is an argument for both NFS and iSCSI over FC.
- One user pointed out that the tools to troubleshoot IP networks are much better than those for FC, another advantage for both NFS and iSCSI.
- SAN expertise is more specialized than IP; it's harder to find and retain experts (and they're usually paid more).
However, there aren't many vendors offering storage systems that support NFS. There are literally dozens of SAN-based storage systems, but only a handful of NFS or NAS storage systems in the market. Customers want choices, and the fewer there are the less likely they will go down a particular path. And these are good reasons because competition fosters innovation, cost-effectiveness and better service.
NFS for VMware has the potential of changing the data storage landscape, but sadly, it probably won't. It's a major challenge to educate the market; there's an enormous amount of incumbent SAN storage systems; and there's no one taking up the mantle to fight this good fight. Even NetApp has lost its fervor for NFS and has instead taken a "we provide whatever protocol you want" attitude, responding to the market vs. driving it. That isn't to say NetApp isn't promoting the use of NFS with VMware, but it's not a core strategy and is only one of many things the company talks about. BlueArc and Isilon Systems are focusing on NFS for VMware, but they don't have the same resources or generate the same level of awareness as the big storage vendors. However, if NFS for VMware is going to take off, these two vendors are sowing some seeds and will be in a position to reap the rewards.
NFS is a more highly virtualized protocol than Fibre Channel and even iSCSI. As a result, it works much more easily and efficiently with VMware. If NFS is to become the dominant VMware protocol, it's probably not the storage specialists that will make this happen but rather the VMware administrators who want highly virtualized networked storage without having to be a storage expert. The implications of this are significant as VMware continues to proliferate and those who manage these environments will have influence as they decide what they need to be successful.
BIO: Tony Asaro is senior analyst and founder of Voices of IT.
This was first published in June 2010