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By | Timothy Prickett Morgan 22nd April 2011 05:00

Brit outfit rolls own virtual server appliances

Rack and roll

A British consulting company that specializes in server virtualization was so frustrated by the mismatch between general purpose x64-based servers and what the popular hypervisors from VMware and Citrix Systems required that it has rejigged itself into a hardware vendor pushing what it calls virtual machine appliances.

Virtual Machine Company, based in Cambridge, was founded two years ago by Steve Barnett and Nick Hudson to do virtual machine installations at the financial giants in the City of London.

Barnett, Hudson, and a number of the early employees at the company had worked in the high performance computing and telecom fields, so they had experience with systems and modifying them to run very specific workloads. They had no intention of getting into the hardware business.

"In our consulting engagements, we discovered that we could never quite get the right mix of cores, memory slots, RAM speeds, and other features that would let the hypervisors run optimally," Barnett tells El Reg.

One big issue was that on many general purpose server designs, as you add more memory sticks or fatter memory sticks, the speed of the memory has to be geared down to keep the system from choking. So VMC built a few prototype machines and proved that you could tune up a box specifically for a given hypervisor and deliver more performance than you could with a generic box from Hewlett-Packard or Dell.

Since the initial Virtual Server Appliances were launched a little more than a year ago, VMC has gone to motherboard and system maker Super Micro to create its own custom motherboards that offer fat memory capacities using dual-ranked 8GB DDR3 memory sticks but also allow for the memory to run at 1.33GHz even in large banks and even running at the lower 1.35 volts (which saves on heat). The memory is ECC and has chipkill scrubbing as well.

VMC 1200 Series Virty Server

The VMC 1200 Series virty server appliance

The VMC appliances are based on the Opteron 6100 processors from Advanced Micro Devices, and use its SR5690/SP5100 chipset to glue processors to the peripherals in the system.

The company has standardized on the twelve-core Opteron 6164HE processor, which has an ACP rating of 65 watts and which spins at 1.7GHz. To VMC's way of thinking, the extra heat created by the faster 80 and 105 watt parts are not justified by the performance those extra clocks bring, not when the real issue in a server running virtual machines is memory, disk I/O, and network contention.

That is why the VMC machines don't use disk drives, but rather come with a single 100GB flash-based SSD from Intel, which stores the virtual machine hypervisor and other systems-level software needed in the appliance.

The SSD has a very high I/O bandwidth – more than what a slew of disks could deliver, if you could jam them into a 1U or 2U rack-mounted server, which you can't. The SSDs also generate a lot less heat than disk drives, and disks are not necessary in the appliances because for most customers installing private clouds, machines are installed in parts or even in threes for n+1 redundancy.

Waste of bent metal

Most customers hook their virty servers up to storage area networks anyway, so putting in slots for disk drives into a server is a waste of bent metal.

Because the machines are mirrored at the network level inside a cloud, you don't need to mirror data inside the machine, which cuts down on heat, weight, and cost. This flash drive is set up with a VMFS, LVM, or NFS file system, whatever the hypervisor requires.

Having dealt with the memory bandwidth and file I/O bandwidth issues with its appliances, VMC goosed the network bandwidth because this is another area where general purpose machines don't get it right.

Most 1U or 2U rack servers have two Gigabit Ethernet ports, and if you are lucky, maybe four (as in the well-designed Sun Fire machines from the former Sun Microsystems). The VMC appliances have eight Gigabit Ethernet ports.

The VMC 1200 appliance has two sockets loaded up with the Opteron 6164HE processors and has 24 main memory slots, offering up to 384GB of main memory using 16GB memory sticks. (That is the maximum supported by the integrated DDR3 controller on the Opteron 6100 processor for a two-socket machine.)

Memory capacity

These memory sticks are too expensive for most people, so 192GB is the practical top-end memory capacity using the 8GB sticks that VMC sells in the appliances in its standard configurations. The VMC 1200 dissipates about 119 watts when idling and about 307 watts peak under load, hosting VMs and doing lots of work.

"We could never quite get the right mix of cores, memory slots, RAM speeds, and other features that would let the hypervisors run optimally"

In an entry setup, this 1U rack-mounted machine comes with two processors, for a total of 24 cores, 64GB of memory, and one 100GB flash drive; this configuration costs $15,500. Pushing the memory up to 192GB raises the price to $24,000.

The VMC 2400 appliance is a 2U rack server that has four of the Opteron 6164HE processors, for a total of 48 cores, installed in the base box. The machine has 32 memory slots and supports a maximum of 256GB using 8GB sticks. It has a peak power load of 720 watts; idle power consumption figures were not available.

The initial configuration of the VMC 2400 has the 100GB SSD plus 128GB of main memory; it costs $27,000. Doubling up the memory pushes the price to $35,000. VMC is working on a configuration using 16GB memory sticks, which would allow 512GB of capacity for those 48 cores; pricing has not been announced for this fat memory support yet.

If you require "near bare-metal speeds," VMC has some tricks it calls the Infinitely Radical upgrade that allows it to kick the performance up another notch.

Details of this were not available at press time, but it stands to reason that it involves using faster and hotter Opteron 6100 processors and fatter memory sticks to boost the performance of the server appliance and therefore the number and size of the virtual machines that can run on it.

Pre-tuned hardware

The VMC appliances come pretuned, right out of the box, for either VMware ESXi or ESX Server 4.0 or 4.1 or Citrix Systems XenServer 5.5 or 5.6. The tunings are important, so you have to order the right machine – although the tunings can be changed, of course, if you switch hypervisors.

The performance and performance per watt improvements that VMC is claiming that its "precise design" approach yields are significant. Using the Geekbench suite of virtualization benchmarks, Barnett says that a two-socket VMC 1200 appliance with 24 cores (that's a 1U box) can deliver 80 per cent of the virty performance of a four-socket Hewlett-Packard DL580 G7 using eight-core Xeon 7500 processors ¬– and do so burning 30 per cent less power and taking up one quarter of the rack space.

Another way of saying this is that four VMC 1200 appliances will do more than three times the VM hosting as the DL580 G7, and do so in the same space. More importantly when it comes to software pricing, the VMC appliance has half as many sockets as the DL580 G7, and that can radically lower the cost of VMware vSphere server virtualization tools.

Of course, Intel has just goosed the processors used in this machine with ten-core Xeon E7 processors, so the DL580 G7 can now have 40 cores and twice as much main memory and this comparison is already history. But it is illustrative, nonetheless, of what VMC is trying to accomplish with its appliance designs.

Under our control

You might be thinking: How do the VMC appliances link into VMware's vCenter console and into Citrix Systems' XenServer console, which are used to manage the hypervisors and all of their add-on goodies. Barnett gave a very funny, and once you think about it, a very logical answer:

"They don't," he said with a laugh. "We need to have this sort of thing under our control."

Again, here comes some experience in the telecom and HPC business. Barnett said that rather than try to support two different toolsets for controlling the appliances, based on whether they use ESX Server or XenServer as the hypervisor layer, VMC created its own console, called the Virtual Estate Manager, that talks directly to the APIs in these two hypervisors and, from an administrator's point of view, masks the differences.

This approach will make it easier to support Microsoft's Hyper-V and Red Hat's KVM hypervisors down the road when customers start asking for them, and it will mean that VMC's customers won't have to master a new tool. You can, of course, use vCenter and XenCenter if you want to.

The VMC appliances do not include the cost of the hypervisors, which you need to license from VMware or Citrix. It does include the Virtual Estate Manager, which monitors both the physical and virtual performance of the appliances.

The company also tosses in a year of free In-Cloud Services, which is remote babysitting of the appliances performed by VMC's remote monitoring systems. The In-Cloud service can also remotely host any of your VMs in the event that you need to take your own appliances down for maintenance. ®

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