Production databases find a home on IP SANs

In a presentation at the Storage Networking World (SNW) conference, Steve Remsing, senior systems administrator for Dow Chemical, detailed his company's painstaking test process for Oracle 10g R2 on different combinations of Windows, Linux, Fibre Channel and iSCSI. Remsing said in the presentation that Dow Chemical now has plans to push multiple Oracle databases of under 1 terabyte (TB) onto Network Appliance Inc.'s (NetApp) FAS270c iSCSI array. He didn't say exactly how many or what specifically they were used for, other than to say they were for data collection and retention for research.

"We've shown we could get it to work," Remsing said. As for the chief reason for going with iSCSI over Fibre Channel, Remsing gave the same answer as the little guys: cost. He said he couldn't get into how much the company saved by moving from Fibre Channel to iSCSI, but said he was intrigued by the idea of using regular server network interface cards (NICs) and standard Cisco Gigabit Ethernet (GigE) switches rather than specialized Fibre Channel equipment.

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Remsing said he had no worries about the reliability of iSCSI, but that he would keep an eye on performance. "We will look at adding TCP/IP offload (TOE) cards or moving some applications to Fibre Channel if that becomes necessary," he said.

"We believe that more and more companies will use iSCSI for mission-critical applications as a natural progression in its adoption cycle," said Tony Asaro, analyst with the Enterprise Strategy Group (ESG). According to Asaro, ESG Research surveyed 511 companies and found that 17% of these companies were already using iSCSI and another 20% planned to in the next 24 months. "Of the early adopters, 50% were already using iSCSI for Tier-1 mission-critical applications, and 37% of planned adopters intended on using iSCSI for Tier-1 mission-critical applications. "

Web-based software and mobile information services company AirClic U.S.A., based in Newtown, Pa., also has had no qualms about storing Oracle data on iSCSI. AirClic told SearchStorage.com that it had also tested the NetApp system Dow Chemical plans to use, but found EqualLogic Inc.'s latest SAS-based array, the PS3800XV, a better deal for both cost and manageability over both NetApp and EMC.

When it began to explore networked storage again over the winter of 2005 and 2006, AirClic set out to purchase an IP SAN from the start because of the lower costs as compared to Fibre Channel and the ability to use standard NICs and Cisco Systems Inc. networking switches.

Five years ago, according to Andy Monroe, vice president of technology at AirClic, the company had run a Compaq Fibre Channel SAN, but a reorganization left that technology stagnating on the floor. Currently, the company's services include processing data from mobile phones, barcode scanners and sensors in a customer's environment, which AirClic then runs through an Oracle database in order to model workflows for the customer. So, for example, a company employing security guards could receive reports from AirClic on whether or not its employees, wearing devices that trigger sensors in the environment, have made assigned rounds.

Monroe said he never had any qualms about putting the company's production Oracle database on iSCSI storage. "There's a perception that iSCSI isn't for a high performance database," he said. "But for our purposes, throughput speed over Fibre Channel didn't make as much of a difference as drive speed -- 1 Gbps, 2 Gbps or 4 Gbps was not as relevant for us as drive speed for processing information out of our database."

When considering a SAN this time around, the company went for EMC's Clariion first, and also considered NetApp.

EqualLogic beats out EMC and NetApp

In testing, however, "we were able to get the same results in our testing of the [EqualLogic] PS3800 against an EMC CX500i -- the same total number of disks and speed of disk at 15,000 rpm, for a lower cost," he said. In tests running small random I/Os using Oracle's Orion Calibration tool, which is designed to simulate Oracle workloads, Monroe said, "we were seeing about 4,000 IOPS on the EMC unit and about 4,200 IOs per second (IOPS) on the EqualLogic unit when using Iometer."

He added, "We were trying to isolate the performance of the disks and also be sure there wasn't any real difference between iSCSI and Fibre Channel with those types of workloads."

Along the line, AirClic also evaluated NetApp's FAS270 array. According to Monroe, NetApp brought in one of its own engineers with the 270 and spent five hours trying to get the test machine, a Dell 2850 running Windows server 2003, set up. "They used several service packs and couldn't get the logical unit numbers (LUN) to present to the server," he said.

According to Monroe, even once it was up and running, the graphical user interface (GUI) was not intuitive. "We couldn't figure out how to create a volume, or perform iSCSI authentication intuitively -- we found ourselves going through a lot of documentation," he said. "The impression I got was that this unit was really aimed at being used for Fibre Channel and had iSCSI support just added on top of it."

After exhausting those options, Monroe was referred to EqualLogic by a reseller, and quickly decided to purchase after being sent a test PS100 array in January.

"We are not storage experts by any means," Monroe said. "But we got that one up and running in 20 minutes."

Several months later, AirClic became a beta tester and then an early adopter of EqualLogic's new SAS array, the PS3800XV -- in all, the company's networked storage environment today comprises 6 TB, most of it on 15,000 rpm SAS drives on the newer array.

The SAS drives, Monroe said, helped assuage any worries about another iSCSI problem -- reliability. EqualLogic's automatic load balancing within its modular arrays and hot-swappable components also helped, he said.

Moreover, analysts said that AirClic isn't necessarily in the minority -- the traditional performance and reliability worries about iSCSI, especially in small and midsized enterprises, are becoming a thing of the past.

"I am seeing more smaller enterprises put IP SAN on their roadmap for mission critical workloads. Over the next 24 months, this will become a completely standard expectation from customers -- the economics will be very compelling," said Brad O'Neill, senior analyst with the Taneja Group.

Not perfect by any means

Though he's happy with its reliability, management and cost, using the EqualLogic array hasn't been a totally ideal experience with his Oracle database, Monroe said. He still prefers to use (and manage) a separate tool for backup -- Oracle's Hot Backup and Oracle's DataGuard for replication -- rather than the baked-in snapshot and asynchronous replication capabilities offered with EqualLogic's arrays.

Another issue is EqualLogic's support for Linux. "Oracle prefers to run on Linux," Monroe said. "That's just the nature of the application." But while EqualLogic offers what Monroe calls "fantastic support" for Windows applications, including multipathing for better traffic throughput and failover within the array using Microsoft's software iSCSI initiator, on the Linux side, a software initiator has to be combined with a costly hardware host bus adapter (HBA) to get the same effect.

For now, Monroe said he simply mirrors his database server for failover using an active-active cluster, "But a software initiator that would support multipathing on the EqualLogic array would save me that hardware cost," he said. "And if EqualLogic is trying to get into the game to support all platforms, they could address this gray area better."

"The issue that [Monroe] raised is valid…the difference between Windows and Linux/Unix software initiators is not often discussed," said Dylan Locsin, public relations manager for EqualLogic, in an email to SearchStorage."MPIO [multipath I/O] from Windows is a great thing, and we'd love to see Linux operating systems have a similar feature. Software initiators are best developed by the operating systems suppliers, so building a better initiator is not really an issue EqualLogic alone would solve."

According to Locsin, EqualLogic typically recommends that users look into lower cost HBAs, such as those offered by Silverback Systems Inc.. "These may be half the cost of previous products, perhaps as low as $200 per port," Locsin said. "There are still other reasons customers may want to have HBAs, as they still provide boot-from-SAN capabilities."

Another option EqualLogic recommends users consider is NIC teaming, a process of grouping together several physical NICs into one through scripting. "Ultimately, this isn't as good as MPIO, but in many environments it meets deployment needs," Locsin said.