Virtual servers meet VTLs

Posted on May 01, 2008


By Kevin Komiega

The explosive growth of server virtualization is fueling a change in the way end users evaluate and ultimately choose their backup systems. The shift has put virtual tape library (VTL) vendors (as well as all other storage providers) on notice that compatibility with market–leader VMware’s ESX Infrastructure technology is no longer just a nice thing to have: It’s a must.

When Sterling Testing Systems, a private provider of pre–employment screening services, began a multi–year server virtualization and consolidation project the company’s IT group quickly realized that they would need a high–speed virtual tape library (VTL) to accommodate rapid capacity growth, improve backup performance, and support some of the more advanced data–protection features found in VMware. This made support for VMware a must–have feature of any technologies the company would evaluate.

In the past, supporting physical servers with storage resources was a straight–forward proposition, but no more. Andrew Madejczyk, vice president of global technology operations at Sterling, says playing in the virtual world is a whole new ballgame.

“When we began, we had recently purchased a couple of EMC Clariion CX500 SAN systems, but what we found out in a short period of time as we embarked on our server virtualization project was that the original plan for capacity was well off,” says Madejczyk. The capacity planning problems were not just in primary storage. Backups were causing headaches as well.

“We had physical servers that required some attachment to networked storage, but nothing like the requirements of virtual servers,” he says. “We need a lot of space to accommodate all of our VMDK files, which means we have to dig deeper on determining what our capacity requirements are going to be.”

A virtual machine encapsulates an entire server or desktop environment in a file. The VMDK specification describes and documents the virtual machine environment and how it is stored. Patch, provisioning, security, management, backup, and other infrastructure solutions for virtual machine environments all heavily depend on the VMDK format to function properly within VMware infrastructures by allowing partners and ISVs to understand how virtual machine disks are configured and, in the case of storage, how to back them up.

Sterling’s storage requirements run the gamut. The company backs up virtual machines that range from 10GB to 70GB, depending on the different applications they host. “I would love to tell you that capacity planning is an exact process and in certain cases it is, but when you are a growing company it’s a lot to keep up with,” says Madejczyk.

One of Sterling Testing Systems’ biggest pain points was the backup window, which sometimes ran for up to 12 hours and bogged down performance during peak production periods.

After evaluating a number of VTLs, Madejczyk and his team decided on an implementation using Sepaton’s S2100–ES2 enterprise VTL appliance. The S2100–ES2 can handle backup sets of any size at speeds of up to 34.5TB per hour.

The S2100–ES2 VTL can scale in capacity from 7.5TB to more than 1.2PB of physical space, and performance can be increased through the addition of Scalable Replication Engine (SRE) nodes, which bring up to 9,600MBps of added speed apiece.

Madejczyk’s expectation was a significant increase in performance and a subsequent reduction in the backup window. He says he is still in the process of fine–tuning his VTLs, but overall the implementation has been a success. “The daily backup window went from about eight hours down to three, and weekly and monthly backups went from 24 hours down to 12 hours,” he says.

Approximately 90% of the company’s servers, which host everything from Microsoft Exchange and SQL Server to proprietary applications and back–end fulfillment systems, are virtualized.

Madejczyk adds that the performance of the S2100–ES2 allows Sterling to back up its snapshots directly to the VTL. “It also lets us adjust our snapshot frequency/retention times for optimal protection and cost savings.” Sterling retains one snapshot per day for 21 days, saving more than 100TB of costly near–primary storage.

Sterling Testing Systems’ introduction to the Sepaton VTL was a 22TB configuration. Madejczyk plans to scale the system as the company keeps more snapshots and moves to a tiered approach to backup and archiving in the future.

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