This content is part of the Essential Guide: VMware VSAN features and realities
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Can VMware VSAN offer RAID-like safeguards?

Administrators using VMware Virtual SAN have a new way to pool storage from servers, but how dependable is this latest technology offering?

When using VMware Virtual SAN, how is the data store protected when using this virtualized storage arrangement...


VMware's Virtual VSAN is the virtualization company's fledgling effort in software-defined storage, and was first made available in vSphere 5.5. As with most new products, administrators have questions about configuration and how VMware VSAN differs from a more traditional storage setup.

VMware touts VSAN as a way for businesses to leverage the storage they already have in the ESXi hosts and pool that capacity into data stores for VMs. VMware says one advantage with VSAN is it allows companies to scale their storage more easily by adding more disks rather than being locked into a storage array.

VMware VSAN requires a minimum of three hosts -- scaling to 32 nodes -- in a VSAN cluster, while each host providing storage must also have a solid-state drive (SSD) to speed up read/write caching.

Instead of a customary RAID arrangement to protect the data store, the minimum three-host configuration in VSAN provides the security an administrator would want to protect  business continuity in the event of a hardware failure.

"We drive resiliency through software. We don't do hardware RAID. There's no RAID 5, RAID 10. We don't suffer the performance or the management complexity of setting up hardware RAID," said Peter Keilty, senior systems engineer at VMware, during his presentation on VSAN technical overview and best practices at the Boston VMUG User Conference on June 24.

Keilty added that the capacity requirements of RAID are not existent in VSAN.

"We do all the protection at the software level. We make sure we have two copies of the data at any one time in two different hosts so if you were to lose the hard disk or the SSD or the whole host you have another copy of the data somewhere else in the cluster," said Keilty.

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