EqualLogic Mixes SAS, iSCSI

EqualLogic is bringing out SAS arrays as the second step in its strategy to make its iSCSI SANs good for more than "junior league applications."

EqualLogic today unveiled the PS3000, which offers Serial Attached SCSI (SAS) arrays. EqualLogic's previous systems all used SATA drives. At 15,000 RPM, the SAS drives spin as fast as Fibre Channel. EqualLogic offers two versions of the PS3000 -- one with 15,000 RPM and 150Gbytes drives and the other with 10,000 RPM and 300 Gbytes. SATA disk spins at 7,200 RPM and goes as high as 750 Gbytes. SAS also has a higher mean time between failure (MTBF), which makes it more reliable.

In late July, EqualLogic added virtualization features such as the ability to use multiple storage pools in a SAN, set up consistency groups to automate multi-volume snapshots, and manage different RAID levels in a SAN as one group. (See EqualLogic Firms Up Virtualization.)

The virtualization features together with higher performing drives will let customers set up tiered storage with SAS for applications that require higher performance with SATA as a second tier for archived and less frequently accessed data. The SAS drives spin faster than SATA, which spins at 7,200 RPM and cost more than SATA but less than Fibre Channel.

EqualLogic is the actually the second IP vendor to offer SAS -- Nimbus Data shipped iSCSI SAS systems in March. (See 10-Gig IP SANs Hit Bleeding Edge.) StoneFly Networks says it will also include SAS drives later this month for in an IP SAN. (See A New Landscape for Disk.) But EqualLogic has the largest market share among dedicated iSCSI vendors, trailing only Network Appliance and EMC.The question is: Will IP SAN customers want to pony up more money for less-than-Fibre Channel performance? Pricing for EqualLogic's SAS arrays begins at $65,000 for 4.8 Tbytes of 10,ooo RPM disk or 2.4 Tbytes of 15,000 RPM disk. That's roughly $20,000 more than what they'd pay for a system with 4.8 Tbytes of SATA drives. The SAS systems will be available next month.

EqualLogic CEO Don Bulens says IP SAN vendors are fighting the notion that iSCSI is for low-end systems and not fit for high-performance applications.

"The perception is iSCSI adoption is for people willing to put junior league applications on unreliable disk on Ethernet connections," Bulens says. "For pure play iSCSI providers, the application and reliability you can deliver with SAS is compelling in the market. It gives you a mix of higher I/O performance on one hand, and the ability to migrate data from higher performance to lower performance on the other."

Bulens says his company is coming off its first profitable quarter and has more than 1,500 customers. He expects about one-third of EqualLogic customers to add SAS arrays, but he's not sure how many new customers SAS can attract.

"That's the multi-million dollar question," Bulens says. "Will it help us win business from clients who wouldn't believe they could get adequate performance from SATA systems?"Customers finding iSCSI good enough may be reluctant to pay more unless they have a compelling reason to upgrade.

"SAS will be more expensive, but you need that ability to mix and match if you have a tiered strategy," says analyst Stephanie Balaouras of Forrester Research. "There are apps that need high performance. People have been pushing the boundaries of SAS, and some will feel more comfortable with higher performing drives. SAS fills that gap."

Andy Monroe, IT manager of mobile device manufacturer AirClic, is one of the EqualLogic customers interested in SAS. He's been beta testing the new PS3000 arrays with drives and expects to purchase a 32-drive array for 4.8 Tbytes.

"The real driver for us is we have several different types of databases," he says. "One is high transactional with small reads and writes, and random I/Os. The laws of physics preclude you from using SATA drives -- you either add more spindles or get faster drives. I thought it would be more cost effective to get faster drives."

Monroe will continue to use his EqualLogic SATA for data warehousing and archiving, while running the databases that demand high performance on the SAS arrays.He says the extra cost of SAS doesn't bother him because he would have to buy even more SATA to get the same performance. And he says using SAS for high performance keeps him from having to buy Fibre Channel. Even with iSCSI chugging along at 1-Gbit/s Ethernet and Fibre Channel at 4-Gbit/s, Monroe doesn't miss Fibre Channel.

"It saves us $100,000 a year not having to keep a [Fibre Channel] storage engineer on staff," he says. "Everybody here knows Cisco equipment and how to hook up Ethernet, so it's no problem."

Then there's MediSyncCTO Roger Cass, who considers talk about drive types merely marketing spin -- at least for the types of applications he runs. MediSync handles accounting, billing, scheduling, hiring, and staff management for physicians and healthcare organizations.

"If the price is the same, we'll take SAS. If there's a premium, we're fine with SATA," Cass says. "We don't have high peaks and high sustained loads. I still haven't exceeded the performance of the existing array."

Cass is running an EqualLogic PSE100E with 10 drives and 1.6 Tbytes. He uses RAID 5 plus 0 and says he's only lost one SATA drive in more than two years."I'm not picky and choosy about what kind of drives I use, except for the capacity," he says.

Dave Raffo, News Editor, Byte and Switch