The VSAN uses both flash and HDDs, both of which must be in each participating server, to create a high-speed cache and a slower tier of less used data. VMware recommends using standard high-capacity SATA HDDs, which helps to lower the cost of the pooled capacity, Farronato said.
For external storage, VMware gave a technology preview of what it calls Virtual Volumes. This software allows storage arrays to deal with stored data on a per-VM basis rather than by traditional ways of organizing storage such as LUNs (logical unit numbers). That means each VM can have its own settings for services such as snapshots and replication, Farronato said.
The company's policy-based control layer is designed to give administrators the fine-grained control they need to establish policies for each VM. After those policies are set up, the control layer assigns them to the particular VM so they remain throughout the VM's lifecycle.
That's a step forward from traditional techniques of deploying storage settings for different applications, Farronato told a VMworld session on Monday. Administrators have had to manually configure settings for each application's use of storage and then go back in to modify those if the requirements change, he said. The company's new policy-based control is also an advance from its own capabilities in the current version of vSphere, which just lets users assign standard profiles for VMs with different levels of priority.
Also at VMworld, the company announced technology for HDD storage that came from its acquisition of Virsto earlier this year. The Virsto software can help HDDs deal with multiple VMs running multiple applications, a situation that can lead to uneven performance. Key to solving this problem is placing the bits from each application in sequential order so that getting to the data doesn't require jumping all over the disk, Farronato said.
The company also introduced vSphere Flash Read Cache, which it called an easier way to assign server-based cache on a per-VM basis. When a VM moves from server to server with VMware's vMotion function, this new feature can move its cache in real time, Farronato said.
Policy-based control and other advances in storage virtualization by VMware and its rivals are still emerging technologies, Gartner's Wolf said. Early adopters will start using VSAN in test and development environments next year, but for production use enterprises will probably remain cautious about it through 2016, confining it to applications with lower service-level requirements, he said.
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