San Francisco Users Group Takes on iSCSI
Each month, the San Francisco Networking Technologies Users Group (SFNTUG-- http://www.sfntug.org ) hires top professionals to teach and lead SFNTUG members through loading and configuring Windows Server-related hardware and software. These "loadfests" are well attended and often provide SFNTUG members their only source of training for leading-edge technology. During one 7-hour training session in October, the SFNTUG took on the task of configuring an eight-node Windows Server 2003 cluster and connecting 35 Windows servers to an Internet SCSI (iSCSI) Storage Area Network (SAN).
"We needed an inexpensive SAN solution that utilized off-the-shelf components, and iSCSI got the job done," says Doug Spindler, president of the SFNTUG. To contribute to the loadfest, participating members brought their own servers, each of which had two NICs and Windows 2003, Enterprise Edition installed. One NIC on each machine was connected to an Ethernet network, and the other NIC was configured to connect to an iSCSI storage concentrator provided by StoneFly Networks.
The loadfest used Microsoft's free file system driver, the Microsoft iSCSI Software Initiator Version 1.01, which redirects file system activity to a particular NIC. Here's how the driver works. First, the iSCSI Software Initiator traps the file system commands and encapsulates an iSCSI command within a TCP/IP packet. The initiator redirects this packet through the NIC and across the network. The StoneFly iSCSI storage concentrator (an iSCSI gateway) receives the TCP/IP packet, reads the encapsulated iSCSI commands, then directs the data packet to the appropriate SCSI disk drive connected to its gateway.
Before you can start redirecting traffic to the storage concentrator, you must first configure it by using the StoneFly Networks management UI. The basic idea is to assign SCSI disk storage to the attached servers. "We assigned disk storage to all 35 attached servers in less than a half hour. The StoneFly tool is very intuitive," says Spindler. After the StoneFly concentrator is configured, it's ready to receive data traffic.
StoneFly supports all levels of RAID storage, so you can create highly redundant disk storage configurations. In addition, because each of the 35 servers included Windows 2003, Enterprise Edition, SFNTUG members were able to create an eight-node cluster by using the built-in Microsoft clustering software. "Once we had our cluster set up, we started unplugging servers one at a time to see if the other server nodes in the cluster would pick up the load. Each server was running Windows Media Player \[WMP\] and playing an MP3 play list. As each server was unplugged, the failover server in the group picked up the load and started playing the appropriate tunes," says Spindler.
Spindler notes that achieving maximum performance wasn't a key objective of the loadfest. The main point of the exercise was to familiarize SFNTUG members with Windows clustering technology and iSCSI SAN technology. To improve iSCSI performance, you'll need to make sure that the iSCSI concentrator contains a TCP/IP Offload Engine (TOE) card. In addition, the iSCSI SAN will need multiple NICs to load-balance data traffic across the network.
The fact that user groups are teaching iSCSI technology demonstrates to me that iSCSI is starting to move out of the technology acceptance phase into a corporate early adopter phase. This phase is the critical testing phase that will determine whether iSCSI becomes a mainstream tool or a niche solution.