After outgrowing its Hewlett-Packard (HP) Co. LeftHand iSCSI SAN, human resource outsourcing firm AlphaStaff switched...
to Compellent's Storage Center and stuck with iSCSI for simplicity while adding solid state drives (SSDs) to eliminate latency problems.
Fort Lauderdale, Fla.-based AlphaStaff handles its client companies' payroll and benefits processing, which puts a great deal of emphasis on its ERP system. That led it to implement a LeftHand Networks SAN in 2004 before HP acquired LeftHand. That iSCSI SAN served the company as it grew from handling HR functions from 6,000 to about 80,000 employees, according to vice president of IT operations Jack Rahner.
During that time, Rahner said, AlphaStaff also went heavily with VMware. "VMware came into its own as more of a product for the masses," he said. "I never considered it production-ready for high-end applications such as ERP at first, but VMware made believers out of me and tons of people."
The move to VMware for production data plus "a tremendous explosion in data" prompted Rahner to look for a larger SAN system two years ago. At that point, AlphaStaff had 60 TB in its Fort Lauderdale and Atlanta data centers. Rahner said he thought it was easier to build out his HP/LeftHand storage than replace it, but eventually ran up against performance limitations.
"We made the right choice at the time with LeftHand but we were starting to get to the point where we could not scale," he said. "It had nothing to do with iSCSI, but our problems were with latency."
Rahner decided to look around, but didn't like what he saw from the larger storage vendors.
"We looked at HP's EVA, NetApp and others," he said. "HP hasn't had a new thought on the SAN market for quite some time. I used to like NetApp because it challenged EMC, but NetApp hadn't come out with anything new in awhile. NetApp's attitude was like EMC's, 'We're NetApp, we don't have to bend, we're the best.'"
Rahner said he was impressed by Compellent's technology, especially its Data Progression automated tiering software. "The idea of block level tiered storage automated by algorithm was too much of no-brainer," he said.
Before taking the plunge, though, Rahner and a few of his engineers went to Compellent's Eden Prairie, Minn., headquarters and spent a week testing Compellent's performance on AlphaStaff's ERP system.
"Switching SAN vendors is like changing wives in a way, all your eggs are in one basket," he said. "So we did an extensive evaluation. We saw a 60 percent average increase in performance over LeftHand, and Compellent's ease of use became quickly evident. It was cheaper megabyte for megabyte than what NetApp and some higher-end HP systems were offering."
That performance was with iSCSI SAN, which meant AlphaStaff wouldn't have to switch over to Fibre Channel. "I knew I wouldn't have to have a dedicated storage engineer," Rahner said. "If I could get on the SAN quickly and use it, anybody could."
While most Compellent customers use Fibre Channel, AlphaStaff stuck with iSCSI only for simplicity and price and added SSDs for performance. Its ERP system uses a UniData database, which runs on a Pick Systems operating system. "Pick UniData doesn't use memory well," Rahner said. "It may see 30 gigs of RAM but will only use two. We had latency issues. We do payroll. A company sends $10 million to AlphaStaff, it wants its employees paid on Friday but it may not send the money until Wednesday. We have a day or less to verify funds, process the transaction, put checks in FedEx and make sure the checks get to all their branches on time. We were driving out and meeting the FedEx plane just before it took off."
He said with SSDs, the time it took to post a transaction dropped from 22 milliseconds to one or two milliseconds. "Multiply that by around 100,000 postings," Rahner said. "That eliminated the need to drive to the airport to meet Fedex so we could meet payroll."
Rahner said AlphaStaff limits its SSD use to the ERP system. It also uses 15,000 RPM SAS and 2 TB SATA on the SAN, and has about 200 TB of total capacity in Atlanta and Fort Lauderdale.
"There's a massive cost per gigabyte with SSDs," he said. "If you have three 146 gigabyte drives, one's a hot spare and one's a mirror, so you're down to one. It's cost prohibitive to use it for everything."
Rahner said he'll eventually move to 10-Gigabit Ethernet to increase iSCSi performance. "We could use Fibre Channel for backups because we're slamming data through the network, but beyond that, we're fine with iSCSI," he said. "With 10-gig iSCSI, I see us not having to move to Fibre Channel."
Rahner said he's happy with Compellent's performance, service and its reporting and management features but has a few items he'd like to see the vendor add. "We're working with them on a couple of things," he said. "I'd like to see quality of service over SAN traffic to prioritize things, and would like more real-time logging features."