SAN FRANCISCO - It used to be that if you were virtualizing your Exchange Servers you might as well have been updating...
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your resume at the same time. No one thought it was such a hot idea.
But during the past year, some of the major virtualization vendors have offered guidance on how to virtualize your major messaging platform without suffering server downtime.
IT interest in virtualizing Exchange Server was in evidence at VMworld 2009 here last week, by a packed session on virtualizing Microsoft Exchange. The goal is to simplify management, increase resource utilization and cutting server downtime. For instance, live migration capabilities in VMware, XenServer and in Hyper-V R2, the latter which is due out next month, let users move virtual machines (VM) to different servers during maintenance or when doing disaster recovery.
Plus, the high availability features built into virtualization software promises uptime for virtualized Exchange Server instances. A Citrix whitepaper on virtualizing Exchange Server 2007 promises increased server and storage utilization, and as a result, lower equipment, power, and cooling costs.
During the session, VMware executives suggested that virtualizing Exchange might help cut costs. But cost reduction shouldn't drive a decision to virtualize Exchange server, said Delmar Tanner, an Exchange Server administrator from Grow Financial Federal Credit Union in Tampa, Fla..
"I don't see where the cost savings part fits in - the hardware upgrades you need to do to virtualize Exchange costs money and VMware's software really adds up," Tanner said. "The real benefit is that it is easier to manage Exchange in a virtual environment, especially for doing disaster recovery."
New technologies, right storage, better performance
Performance improvements needed for successful Exchange Server virtualization have come from increased processing cores, added network bandwidth and virtualization-optimized chips from AMD and Intel Corp. Microsoft's Exchange Server 2007 is 64-bit only, which has improved the performance of virtualized Exchange Server 2003 by 30%, VMware executives at the conference said.
The 64-bit server offers double the block size (8kb), 32 GB of database cache compared to 900 MB in Exchange Server 2003, a 1:1 read/write ration and a 70% reduction in disk I/O.
Todd Muirhead, staff performance engineer at VMware, said he tested Exchange Server 2007 on vSphere using Microsoft's Exchange Load Generator tool to simulate tasks. Following Microsoft sizing guidelines, in a scenario with eight processing cores in a single virtual machine (VM) and 4,000 users on that VM, Exchange performance was within 5% of the performance on physical machines – a vast improvement from 30% overhead seen in Exchange Server 2003.
Since Exchange taxes storage more than it does the CPU, Muirhead said he also tested storage performance using Fibre Channel, iSCSI and Network File System (NFS) on NetApp's FAS6030. He ran eight VMs, each with 2,000 "heavy" online users - totaling 16,000 users in all. Muirhead said. Fibre Channel outperformed the other storage products, offering the lowest latency, but the other storage options performed "well."
"You don't have to decide on a storage protocol based on performance. If you sized the back end storage with the correct number of disks, performance will be fine with any of those," he said.
Tanner concurred that right-sizing storage is key to getting good performance when virtualizing Exchange. He virtualized 2,500 Exchange Server 2003 mailboxes and oversized storage and disks to ensure the best performance possible.
"Exchange isn't really CPU heavy, the performance overhead is due to storage, so we had to compensate for that with additional storage," Tanner said.
An IT manager from Marvell Technology Group Ltd., a semiconductor company, told IT managers how his company successfully virtualized Exchange Server by upgrading their hardware. The company supported 6,000 mailboxes in a mixed Direct Attach Storage/iSCSI environment with EMC SAN using aging servers, and decided to virtualize Exchange when it came time to upgrade their hardware.
The company now runs Exchange Server 2007 on VMware ESX 3.5 using iSCSI SAN, NetAPP FAS3070C and Hewlett Packard servers, and the performance is solid, said Terence Chong, IT Manager at Marvell, in Santa Clara, Calif..
"We improved our performance with the hardware upgrade, simplified management by reducing our backend servers and reduced the complexity," Chong said.
Let us know what you think about the story; email Bridget Botelho, News Writer
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