For all the back and forth about which virtualization technology is cheaper -- VMware versus Microsoft Hyper-V...
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versus Citrix Systems' XenServer -- cost-sensitive IT professionals now consider networked storage as another place to save money.
For every dollar spent on virtualization software, experts estimate that companies spend at least $2.50 on networked storage -- probably more. Others have floated numbers as high as $16, including servers and services. Admittedly, that's "an extreme number," said Mark Bowker, a senior analyst at Enterprise Strategy Group, but regardless, "storage is the biggest piece of that pie."
Thankfully, there are ways for IT managers to minimize storage spending while still getting the features they need to take advantage of virtualization must-haves such as VMotion and live migration.
IT shops become NAS converts
One place to begin is network-attached storage (NAS) instead of a Fibre Channel storage area network (SAN), said Bowker, because it allows you to avoid the cost of Fibre Channel host bus adapters (HBAs) and switches. Storing virtual machines on NAS volumes also offers manageability benefits, he said.
Rod Lucero, CTO at VMPowered, a VMware reseller in Minneapolis, Minn., goes one step further and specifically recommends NetApp NAS arrays because they can deduplicate primary data for no additional charge. In virtual environments, "that translates to huge savings because virtual machines deduplicate so well," Lucero said. VMpowered customers running NetApp NAS report deduplication rates of 70% to 92%, he said.
A recent convert from Fibre Channel SANs to NetApp NAS/Network File Storage (NFS) is Organic Valley, a cooperative of more than 1,300 family farms that distributes dairy products in 34 states. In 2006, Organic Valley bought its first SAN -- a Dell-branded EMC Clariion -- but in 2008 jumped ship and migrated its 116 virtual machine VMware environment to two NetApp 2050s with 18 TB of capacity.
Organic Valley's technical services manager, Curt Parr, cited complexity, underutilized capacity, and ever-recurring upgrade charges as reasons for the switch.
"Something felt wrong with the EMC Fibre Channel method," Parr said. "Every question I had cost me $5,000 in software that only a consultant could read. They have a big-shop mentality, but that's not us."
In contrast, with NAS and NetApp's management tools, "I look at two things -- I/O bandwidth and total capacity." Thin provisioning has dramatically reduced the amount of wasted capacity in the environment, which used to stand at 50%, and simple tasks like expanding a (logical unit number) LUN that took one administrator 13 hours can be achieved in minutes for operational savings.
In NetApp's case, IT shops can achieve further savings by using iSCSI rather than NAS, said Scott Lowe, the national technical lead for IT consulting firm ePlus Inc. in Herndon, Va., since NetApp does not charge for the iSCSI protocol as it does with NFS, CIFS and Fibre Channel. But VMPowered's Lucero said that NFS is a better choice for environments with stringent disaster recovery needs. Using NetApp's SnapManager for Virtual Infrastructure, an administrator can recover a virtual machine in under a minute, but that same operation from an iSCSI device will take 15 to 20 minutes, he said.
Virtual storage appliances
Some small and forward-looking IT organizations have also begun to consider virtual storage appliances: software that creates a SAN out of a server's locally attached disk drives. Examples include HP's LeftHand Virtual Storage Appliance, StorMagic's SvSAN, DataCore's SANmelody, FalconStor Network Storage Server (NSS) Virtual Appliance, and Seanodes' recently released Exanodes Virtual Machine Edition.
Experience with VSAs depends on the size of an organization. Both Lowe and Lucero said that they had performance and reliability concerns about HP LeftHand's VSA, for example, and would recommend it only for very small environments.
But small environments report good results with VSAs, according to Joel Hurford, the principal of IT consulting firm Mitsis in Dumfries, Va. uses STORmagic's SvSAN for testing and developing applications, and said SvSAN works "as advertised." Setup was "extraordinarily simple" and he paid only $1,300 for a two-host license, high availability, and one year of support. At the same time, the Mitsis STORmagic VSA is supporting only a handful of users. "I don't know what it would be like in a fully loaded environment," he said.
However, Hurford said that he sees a role for VSAs in larger organizations too, primarily in test and dev environments like his. "Even in big environments, they always shortchange the test environment." With a VSA, "I can have a test environment with a SAN, which, even if it's not production, simulates it well enough."
Meanwhile, newcomer Seanodes claims its Exanodes VM Edition will satisfy the performance needs of larger environments. With its roots in storage for high-performance computing (HPC) environments, Seanodes uses a fully clustered architecture to achieve performance that is comparable with standalone arrays, but at a fraction of the cost said Frank Gana, Seanodes' business development director. But no Seanodes customers were available at press time to corroborate Gana's claims.
Bare-bones RAID arrays
Another way to cut costs is to buy a barebones RAID array and use storage features like snapshots, thin provisioning and data deduplication found in VMware vSphere 4. With VMware incorporating so many traditional storage features into its platform, "the question is, how much of this functionality do I really need to get from my storage vendor?" said ESG's Bowker.
Thin provisioning, for example, was a feature previously found only in high-end storage arrays such as 3PAR Data's. Now it's included as part of vSphere 4 Standard Edition, which is priced at $1,118 per processor. Using Storage VMotion, which is included in vSphere 4 Enterprise Edition, administrators can convert existing traditionally provisioned virtual disks and immediately recover any wasted disk space.
Meanwhile data deduplication is available only as part of vSphere's Data Recovery product, included in vSphere Advanced Editions and above. But ESG's Bowker said its' possible VMware will eventually begin doing dedupe on primary data.
But VMPowered's Lucero said he worries about shops relying too heavily on VMware's Thin Provisioning. "It might get people into trouble," he said, because unlike storage administrators, they aren't accustomed to watching over their storage capacity. "I still like the idea of managing storage from the storage side."
Likewise, ePlus' Lowe cautioned against using VMware snapshots in the same capacity as those offered by a tier-one storage vendor. VMware's snapshots have their place: "When you want to do something real quick and protect yourself," he said, but they shouldn't be used as part of a disaster recovery plan. "You can't leave them out there for any length of time," he said. If you do, "you're asking for trouble."
In short, be careful when trying to save a buck on storage, said VMPowered's Lucero. "People are always asking 'What is the lowest-cost storage I can get into?' but the question really should be 'What are my real storage requirements?' he said. "Because if you put in a low-cost array and the I/O subsystem can't handle the demands [of the virtualization platform], they blame virtualization, even though that's not where the problem is."
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