According to Tim Porter, acting network and operations manager, the DOE's Golden Field Office in Golden, Colo., originally planned to use an iSCSI SAN from Dell Inc. EqualLogic for the project, based on the assumption that iSCSI storage would be the most cost-effective option.
However, Porter said, in the department's environment with 50 virtual servers, the Dell EqualLogic PS5000 series array the DOE tested performed at up to 120 IOPS. Atrato's Velocity1000 (V1000) disk array, connected by Fibre Channel (FC) to a parallelized back end made up of SATA disks, was clocked at 750 IOPS out of the box, and was then tuned up to 1.8 Gbps throughput.
"VMware recommended iSCSI, but the performance was just not there in our environment," Porter said. The main problem was I/O contention, as dozens of virtual machines hit the same disk spindles over a Gigabit Ethernet connection.
After the Obama administration assumed office last year, Porter said, the government's focus on renewable energy and energy-efficient technologies increased exponentially. "A year ago, we had 150 people in our office — now we have about 450," he said. The department deployed the Atrato with 160 spindles, for 80 TB raw capacity within rack space comparable to what would have been required to house 9 TB of Dell EqualLogic disk arrays. "If you put together the rack space, power and cooling numbers, iSCSI actually wasn't less expensive than a Fibre Channel attached array," he said.
Porter emphasized that the department continues to use Dell EqualLogic arrays for other projects, and that the decision to go with the Atrato array was based purely on connectivity and other technical considerations rather than vendor. "As the federal government, we're not going to endorse any particular product," he said. "It was a decision to go with a unique set of technologies [from Atrato]."
Atrato's self-healing features do have one direct competitor in Xiotech Corp.'s Emprise self-healing disk arrays, but Porter said he was not aware of Emprise at the time the purchasing decision was made and had not evaluated that product.
Atrato V1000 provides cost and power savings
Atrato's 3U, 160-drive enclosure contains 2.5-inch enterprise SATA disks connected to four floor boards. The controller is external, and customers can pick from a 2U controller by IBM or a more powerful 3U controller from SGI (DOE uses the IBM controller on Atrato's recommendation, Porter said). The V1000 lets users customize the amount of data protection by determining the capacity within the box that will be dedicated to replacing failed drives.
Each Atrato V1000 contains sealed sub-units of disk drives, each of which holds a set of four mini-units inside. Each sub-unit and mini-unit is referred to as a SAID -- a Self-managing Array of Identical Disks. The sealed disk canisters contain enough individual hard drives to offer parity protection for data in virtual RAID groups and to automatically swap in spares if one hard drive should fail.
Porter said Atrato's warranty of five years without requiring hard drive swapping represented more savings for the Department of Energy in terms of management costs. He's also found that despite the high density of the box, the hardware design and airflow make it run cooler than other equipment on his floor. The department is planning to deploy rack sensors to monitor energy consumption, but they're not yet installed. Anecdotally, Porter said, "If you walk up and put your hands behind the EqualLogic boxes, you can feel heat — with Atrato, there's no more [heat] coming out the back than there is coming out of the front."
Still, Porter said there are features that he hopes Atrato can copy from Dell EqualLogic. The Dell EqualLogic PS Series use a simple GUI with software wizards that help in provisioning storage. Atrato's array has to be managed through a command line interface. Dell EqualLogic also offers snapshot and replication technologies natively in its iSCSI SANs, including some deep integration with VMware for snapshot data protection. Atrato doesn't support snapshots natively at all, although a company spokesperson said snapshot support is on the roadmap.
"We've found a way around that by using [Symantec Corp.] NetBackup snapshots," Porter said.