VMware's virtualization quest could help shake up storage, too

The jam-packed VMworld show this week in San Francisco has been VMware’s launchpad for flights deeper into storage, an area that the company thinks is due for more virtualization.

While VMware’s new NSX network hypervisor has sent shockwaves through that industry, the company is also introducing or teasing products that bring some new ideas to storage. The idea is the same in both cases: Let enterprises pool their IT resources and apply them to applications and VMs (virtual machines) as needed.

The highlights include software to pool server-based storage into a shared resource and a tool to bring external storage into the age of VMs. Across both, VMware is introducing policy-based control that’s designed to let enterprises fine-tune their allocation of storage to specific VMs and applications.

Storage virtualization is an industry trend that could affect how enterprises deal with data, Gartner analyst Chris Wolf said. In addition to VMware’s latest strides, Microsoft is doing similar things with its Storage Spaces technology, he said.

“To us, this is really technology that’s inevitable,” Wolf said. Storage virtualization in hypervisors will allow many enterprises to do more with less expensive commodity storage, leaving control of those resources to the software, he said.

However, virtualization of storage and other areas of IT may take more than technology. Steven Williamson, a solutions engineer at industrial supply company W.W. Grainger, said after a VMworld session that his company needs to virtualize its storage as part of an eventual movement into hybrid cloud computing. How to do so raises a number of questions that Grainger still hasn’t answered, but the bigger challenge is organizational, he said. Different parts of IT will need to communicate and cooperate more closely, with someone to oversee and drive the overall transition to the cloud.

On Monday, VMware launched the public beta of VSAN (virtual SAN), its software for pooling server-based flash among multiple physical servers. VSAN creates what is effectively a hybrid storage array using flash and hard disk drives on each of a cluster of servers. The software is designed to be built into the hypervisor. Because of that integration, and because it uses storage that’s close to the server CPUs where applications run, VSAN can simplify storage and lower costs without taking a hit in performance, said Alberto Farronato, director of product marketing in VMware’s Storage and Availability group.

VSAN is designed for workloads, such as VDI (virtual desktop infrastructure), that make intensive use of storage I/O. Tests have shown that a VSAN can match the performance of an all-flash external storage array in this application but costs only 25 percent as much, Farronato said. Both server-based flash and spinning HDDs are less expensive per gigabyte than flash for external arrays, he said.

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.