I/O Bottlenecks Loom On VMware's 'Horizon'

of the impending launch of VMware's Horizon technology should be sending alarm bells through data centers the world over.

VMware says it strategy "seeks to free users from...complex, device-centric computing and deliver a more consumer-focused cloud experience for the enterprise." But this ambitious initiative will include the impending increases in virtual desktops and devices that will be followed by bottlenecks in storage and networking I/O.

"Every operating system has a huge number of I/O caches, page caches, database flushes, and other I/O-related processes, explains Alex Miroshnichenko, founder and CTO of Virsto, which develops virtualization system enhancement products. The problem is that as the number of virtual OS instances increases, their transactions begin vying for resources. "Once you implement those as guests on a server, those I/O have to go through a limited number of tunnels in the physical I/O channel, where they choke up."

A first and proper response is to increase the number of network interfaces and add storage. As the number of virtualized desktops on a server grows, a huge number of highly random, independent disk I/O operations mix together in what has come to be known as a VM I/O Blender. "We realized that the core problem is that the I/O Blender -- the highly random I/O going to disk, kills disk performance no mater what hypervisor you use,"
Miroshnichenko said.

To prepare for the inevitable I/O onslaught, resellers should be ready to propose ways to add more virtualization. That's right; The solution to problems introduced by virtualization can often involve more virtualization.

For example, when a Massachusetts-based biotech research firm I once studied ran out of physical space for its computing resources, it began to look for ways to reduce its footprint by virtualizing some of its servers. Its requirements were so vast, it immediately realized the value of virtual I/O for solving the problems introduced by the world's latest wunderkind.

Companies that should be on the reseller's radar include Xsigo, which removes the physical requirement for network cards and host-bus adapters by virtualizing networking and storage controllers, and Virsto, whose Virsto One turns randomized I/O requests into a sequential stream for faster storage. Virsto claims that depending on hardware, its product can cut storage capacity requirements by as much as two-thirds. It's currently available for Microsoft's Hyper-V; a version for VMware is slated for the second half of thi syear

Following VMware's acquisition of SlideRocket in late April, VMware CTO Steve Herrod wrote in a blog post about the company's vision of "end-user computing in the post-PC era."

It's clear that VMware is looking toward a time when a virtual desktops outnumber physical ones. Will your systems be ready?