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VMware coaxes vSphere 5 upgrades with new VMFS, SRM

Updates to the vSphere file system and host-based replication are the unsung heroes of vSphere 5, experts say.

It’s still in the early days for VMware vSphere 5, but new versions of the Virtual Machine File System and Site Recovery Manager are emerging as prime motivators for an upgrade.

Virtual Machine File System (VMFS) 5 was one of the less-heavily marketed aspects of vSphere 5, but users say it has significant benefits, especially its new unified block size that many say will make provisioning Virtual Machine Disk format (VMDK) files simpler.

With VMFS-3, the largest VMDK file possible with a 1 MB block size was 256 GB. Larger blocks of 2, 4 and 8 MB were needed to create larger files. Now, VMFS-5 supports a single unified block size of 1 MB, with which it is now possible to create those larger files.

The unified block size translates to simpler management; previously, file sizes were limited by whatever block size a user started out with.

“One of the problems with VMFS-3 and earlier is that the block size you define when you format the data store determines the maximum size of the VMDK files stored on it,” wrote Christian Mohn, network manager for Seatrans, a Norwegian shipping company, in a blog post. “This means that when planning your data store infrastructure, you must have an idea [of] how large your VMDK files will potentially be during the lifecycle of the data store.”

Mohn hasn’t upgraded yet, but he is among several users who told they’re looking forward to the unified block size.

“I can’t wait to get rid of some of the block size restrictions we currently experience on our LUNs,” he wrote in an email.

“I’m impressed with storage features in version 5,” said Barry Blakely, infrastructure architect for Mazda N.A. In previous versions of VMFS, the largest single-extent volume was 2 terabytes (TB). With VMFS-5, this limit has been increased to 64 TB. “I [also] like [the idea of] having one unified block size and up to 64 terabytes per data store,” Blakely said.

“I've definitely heard good things from users on VMFS-5. It's eliminated several limitations from the prior version, and users seem to feel it's simpler and easier to manage,” said Jeff Byrne, senior analyst and consultant for the Taneja Group. “I believe VMFS has to be one of the most underappreciated features of vSphere 5. VMware used to tout VMFS enhancements fairly heavily in new releases, but their marketing focus has largely moved up the stack, and so the cool new stuff in things like VMFS tend to get overlooked.”

SRM 5 is upgrade bait
Some users are speeding up adoption of vSphere 5 because they want the new host-based replication features available with SRM (Site Recovery Manager) 5, according to resellers working with early adopters.

SRM’s new vSphere Replication feature provides replication between sites at the VMDK level, which allows storage at each site to be heterogeneous -- and potentially less expensive than using matching arrays at each end of the wire.

Mark Vaughn, an IT consultant and vExpert, has clients upgrading to vSphere 5 because of SRM 5. “There are still a lot of people right now beginning their DR strategies. A homogeneous hardware setup can be expensive, so it’s very appealing to some people making their first foray into DR to send their last storage environment to the DR site [when] the new one [at the primary site] doesn’t have to match.”

Shannon Snowden, consulting partner with New Age Technologies, also sees SRM 5 driving vSphere 5 upgrades. “It's not so much for great new features in vSphere, it's more for the other version 5 products such as SRM and View.  People specifically upgrading are generally doing something else and the systems get updated.”

Beth Pariseau is a senior news writer for Write to her at

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