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by Bob Verplank, Computer Visions

Virtualization: February 2010

Steve M. Van Frank

Virtualization, a peek into the clouds: Steve started us out with an excellent presentation of the equipment used by Wintek to Virtualize the server operation.

All of Wintek's servers have been virtualized for two years. As you look at the pictures (PDF), Picture three shows the general layout, picture four shows the now unused equipment, in picture five the first two upright blades on the left which do all of the outside work, the third is for backup not in use but ready to go at any time should any of the first two blades fail.

VMware does the work. The virtual machine doesn't have to be in any particular location, it could be anywhere that has lots of storage and high-speed access. This setup is at Wintek. Any of these blade servers may be hot-swapped at any time. One has to allow enough time for the new blade to transfer the data. None of the cabling on the back has to be disturbed at all. That's one of the beauties of this setup. Three parts make up the backbone of the system, XIOtech SAN, VMware, which does the software part, and the blade server.

As you look at the diagram in picture 6, you'll note that everything is redundant, there are two media bays, two SAN controllers, two FC switches, two ESX servers, two ethernet switches, and two firewalls. The hard drives are all run on RAID 10 and therefore mirrored. In case of any failure of any part or glitch anywhere then they reboot and another virtual machine takes over. They have looked at three types of systems and the one just described is by Xiotech and cost about $80,000 in 2007. Every blade server has a dual power supply and a 2 Gb per second data transfer rate. The Xiotech system has state of the art speed, very good equipment, and everything internally redundant.

Dell has a similar system with less redundancy and a smaller not as fast unit and costs about $7,000. Another one by Data Robotics is called a Drobo and , has even less redundancy, no dual power supplies but still enables virtualization at a lower-level and costs $1,500 without any hard drives. The cost of hard drives for each of these systems can be very different because of various data transfer rates that are possible with hard drives available at both ends of the spectrum either at high cost, quality, redundancy, speed or of lower cost, quality, and speed.

Aaron Miller
MED Institute

Aaron told us of his experiences in VMware at MED Institute. In 2001, they had one server. By the fall of 2004 they had 16 servers and were adding approximately 1 new server per month. By adding VMware at that point, today they only have 37 physical servers that do not use virtualization. Additionally they have 12 servers with VMware running ESX 3. These are now running 127 virtual servers with an estimated ability to go up to 250 and with no new server hardware to add. The current operating systems include a mix of Windows servers, XP, Red Hat Linux, and SuSe Linux. Some of the common applications used include Apache, Tomcat, WebLogic, GroupWise, Oracle application server, MS SQL, and Oracle database.

He talked about the dramatic change in utilization. Their current VM environment has 42 CPU cores with a total speed of 124 GHz and 10% being active and 288 GB of memory with 40% being active. They are using VMs for all of their server environments, including software development, demo, test, and production.

Their return on investment can be thought about with the following figures in mind. Rather than 127 physical servers, they have 12 with 127 VMs. Core switch ports, fiber channel switch ports, and cabling have been vastly reduced. The required KVM switch ports are down to four from what would have been a requirement of 127. Their rack space, cooling requirements, and electrical consumption have all remained proportionately lower. A new virtual machine can be set up in 10 minutes as compared to two or three weeks to order, rack, and install a physical server. Management time is greatly reduced due to consistent drivers, fewer SAN volumes, etc.

Some difficulties have presented themselves in hooking up USB devices which has resulted in a substitution of network attached devices which can accommodate up to five USB drives located anywhere on the network. They are using similar devices to accommodate RS-232 hardware peripherals.

A question was asked about the performance of a virtual machine as compared to a physical machine. He described an MS SQL server 2003 with identical software and hardware characteristics, with one being physical and one as a virtual machine. After running a series of identical, automated tests to exercise the application for more than six hours, the virtual machine was one half of 1% faster than the physical machine.

They continue to add services to their existing hardware with zero hardware purchases. They are contemplating an upgrade to ESX 4 to take advantage of its fault tolerance feature for critical applications.

Dane Jackson
Purdue Research Foundation Sr. Network Administrator

At PRF, we use a mix of VMware Server 1.x and 2.x running on top of RHEL5 (CentOS would work fine for what we do and is also free) to host virtual guest operating systems. We implement 802.1q (VLAN trunking) to allow us the ability to host guest virtual systems for PRF, various park tenants, and other clients by hosting them on their own individual/private VLAN.

Managing VLANs in a VMware Server environment is extremely clunky. VMware Server 2.0 does a better job but you still need to know operating system specific details about how to manage its interaction with VLAN tagging.

Never start a VMware guest system as a privileged user (i.e. root/administrator). This allows an administrator of the guest system the ability to turn the host NIC to promiscuous mode and access data to/from other VM guests sharing the same NIC. Dedicating a physical NIC for each VLAN is a good idea for insuring security (though not required and you also lose out on some benefits of virtualization).

Using direct attached storage (DAS) is extremely inflexible when attempting to manage virtual machines. A storage area network (SAN) is highly recommended for a multi-server environment.

Attempting to manage multiple VMware host servers is extremely difficult without a centralized management tool. This is the big difference between VMware for free and VMware for $$$. However, it is heavily suggested you invest in the management tools if you plan to deploy any more than a few host servers.

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