Storage virtualization for affordable disaster recovery

Enterprise data storage customers are increasingly looking to storage virtualization products to improve disaster recovery plans on a budget, including in combination with server virtualization and new array technologies.

Trucking firm Knight Transportation Inc., and municipalities South Windsor, Conn., and Atascadero, Calif., turned to storage virtualization to improve recovery time objectives (RTOs) and recovery point objectives (RPOs) for disaster recovery (DR) purposes without breaking the bank.

Representatives of all three said they were able to keep costs down by improving enteprise data storage efficiency, a prime IT goal during these economic times.

Combining storage virtualization with no-maintenance disk array

Knight Transportation, headquartered in Phoenix, Ariz., provides trucking services to clients from 27 locations. It has approximately 4 TB of data, which until six months ago was stored on a Cybernetics miSAN. "Cybernetics fit our needs at the time we installed it, but we had a lot of difficulty getting it to replicate to a second SAN when we purchased it unless they were physically connected by Ethernet," said Cory Staheli, vice president of information systems. "If anything broke, it took us forever and a day to restore from tape and get the systems talking again."

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Knight Transportation looked at products from several storage vendors, including Pillar Data Systems, Sun Microsystems, EMC Corp., NetApp Inc., Dell Inc.'s EqualLogic, IBM Corp and Xiotech Corp., finally settling on a Xiotech Emprise 5000 system.

In this economic climate, price was king, and the direct-attached Emprise 5000 came in at a much lower price point than competitors. "I looked at all the servers that were going to be end-of-lifed over the next 18 months, and calculated replacement costs with diskless servers that boot off the SAN," Staheli said. "In 18 months, diskless servers alone will pay off the price of the SAN -- that's how low the price point was."

Staheli added that Xiotech's five-year warranty, which comes with a guarantee that no disk swapping will be needed throughout the warranty period, was also seen as an operational cost savings. "We could have put replication software on servers, but that would've involved a lot of management," he said. "The 5000 is modular and we don't have to mess with it."

There was just one problem – Xiotech offers replication with the larger networked Emprise 7000 system, but the Emprise 5000 doesn't come with native replication. "Xiotech introduced us to DataCore," Staheli said. The company installed DataCore's SANMelody software on the Emprise 5000, which added storage virtualization and replication capabilities.

"Any time you add more than one product, things are probably going to be a little bit more complex," Staheli said of the tradeoff. "I was concerned at first about managing both things, but I would do it again – it has been stable and reliable."

South Windsor completes server virtualization project for the price of a SAN

The town of South Windsor also used DataCore storage virtualization software as well as VMware Inc. for server virtualization while implementing its DR plan on a budget. South Windsor converted its servers to virtual machines and implemented three-site disaster recovery for less than the price the town was quoted for a traditional SAN.

Beginning three years ago, the town of 25,000 was looking to go virtual with its servers and add local failover as well as long-distance DR. Its budget for the entire project was approximately $125,000. Director of information technology Scott Roberts said the town evaluated SANs from EMC, and LeftHand Networks Inc. (now part of Hewlett-Packard Co.). It needed approximately 10 TB of capacity to have room to grow and was looking to virtualize three physical servers with VMware. "At the time, another Connecticut county paid $125,000 for one SAN from EMC," Roberts said. "We needed to get our entire project done for that amount of money."

The town spread the deployment out over two and a half to three years to keep acquisition costs manageable, and started with a SANmelody SAN attached to VMware hosts in town hall. It then added a mirror at the police department building, which is connected to the town hall by fiber the town owns. Finally, a third node was added at a remote site that receives data through asynchronous replication. The town had to buy extra disk shelves to attach to its HP DL360 servers, "but that was peanuts compared to licensing the VMware hosts," Roberts said.

There were tradeoffs for the town similar to those considered by Knight Transportation. Roberts and his team must maintain the server hardware as well as the DataCore software. Roberts also said the DataCore interface is less polished than some of its more expensive competitors. "Dell EqualLogic for example is pretty idiot-proof," he said. "DataCore can be a little more thought provoking to get to the same point, but it's 15 minutes versus five minutes [of management time]. It's not the end of the world."

City of Atascadero turns to DataCore for storage virtualization and DR

Systems administrator Ken Phillips of Atascadero said his city of 28,000 faced similar budget constraints and even more stringent recovery objectives when it turned to DataCore for DR and storage virtualization.

"The restore policy in our service-level agreements (SLAs) with our finance department is pretty aggressive for an organization of our size," Phillips said. The town has a four-hour RTO and four-hour RPO, which were tough to meet while making tape backups to send data offsite. "The best case scenario to even get back up and running again was 24 hours," Phillips recalled.

Consultant Pinnacle Technologies brought in SANMelody to Atascadero in late 2007. "What we actually found was that all three of our choices – DAS, NAS and SAN – over five years came out to the same cost, within a few percentage points," Phillips said. "DAS is what we're comfortable with, but the SLAs pushed us toward block storage virtualization for DR."

Storage virtualization options available on the market

While these three users chose DataCore to repurpose existing hardware, there are many software-only alternatives to storage virtualization that offer similar capabilities, including StarWind Software, Open-e, and StorMagic, or host-based replication products like Double-Take. Users have also found more affordable approaches to disaster recovery by turning to cloud storage services like Amazon's S3.


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