Building High Performance iSCSI SAN Configurations

 iSCSI:

IP storage using Internet SCSI (iSCSI) provides opportunity for many organizations looking to extend existing Fibre Channel SANs to stranded servers, or looking to deploy Ethernet-based SANs. It can reduce costs by allowing IT managers to take advantage of existing, familiar Ethernet networks. Often the biggest complaint with new technology like iSCSI is its ability to provide more than simple functionality and connectivity. That argument is addressed by leveraging fast, wire-speed TCP/IP products common to networking today with fast storage systems. This combination can offer maximum performance and efficiency comparable to many Fibre Channel-based solutions.

iSCSI encompasses several components of storage networking. This includes host-based connection devices commonly referred to as initiators, and storage systems known as targets.

iSCSI Initiators can take several forms including:

- Host Bus Adapters (HBAs) with the iSCSI initiator implemented in the hardware adapter card - Software initiators running over standard network interfaces, such as Network Interface Cards (NICs),

TCP Offload Engine (TOE) NICs (TNICs), or iSCSI controllers

iSCSI targets also come in various forms, including:

- Disk storage systems - Tape storage systems - IP storage switches

Since completion of the iSCSI standard in early 2003, a number of standards compliant products have entered the IP storage market. Many of these products have completed interoperability and conformance testing from organizations such as the University of New Hampshire?s Interoperability Lab1 and Microsoft?s Designed for Windows Logo Program2. While many of these products have achieved general interoperability and functionality, most lack the levels of performance necessary to compete against other technologies in the global storage market.

Despite the lack of performance from some IP storage devices, there are a few iSCSI Initiators products that can be used to build high-performance iSCSI SANs to meet high transaction rates and/or high throughput requirements. This note examines the performance capabilities of the McDATA IPS Multi-Protocol Storage Switches and servers equipped with the Microsoft iSCSI Software Initiator and hardware accelerators like the Alacritech Accelerator family of TNICs or Alacritech iSCSI Accelerator family of iSCSI controllers to build such a high-performance iSCSI SAN.

iscsi network:

The objectives of the iSCSI performance testing aimed to show the McDATA IPS Multi-Protocol Storage Switch in conjunction with Alacritech iSCSI Accelerators and the Microsoft iSCSI Software Initiator on Windows-based servers, sustaining wire-speed iSCSI throughput at larger transaction sizes and a substantial transaction rate, measured in Input/Output Operations per Second (IOPs). In the case of saturating a single IP Storage Gigabit Ethernet link, the full-duplex wire-speed throughput is over 210 Megabytes per second. For more details please see Appendix B: Storage Networking Bandwidth.

This test looks at a balanced single test configuration tuned for performance over a broad spectrum of operation sizes. Tests and iSCSI SANs can be more specifically tuned for optimal throughput or optimal transaction rate.

Performance Configuration Details

Test Execution

Alacritech commissioned VeriTest, a division of Lionbridge Technologies, to compare the performance of a number of iSCSI initiator products. Performance reported in this note reflects the subset of testing specific to the Alacritech and McDATA configuration.

Equipment

The iSCSI server configuration used an SuperMicro X5DPE-G2 motherboard with dual Intel Xeon processors, and an Alacritech SES1001T iSCSI Accelerator. Alacritech's acceleration solutions are based on the company's high-performance SLIC Technology architecture. Products based on SLIC Technology remove I/O bottlenecks for both storage and networking systems by offloading TCP/IP and iSCSI protocol processing. The server used the Microsoft iSCSI Software Initiator, version 1.02, to perform iSCSI connectivity. The iSCSI Accelerator was connected to the network through a Dell PowerConnect 5224 Gigabit Ethernet switch to the McDATA switch.

A McDATA IPS3300 Multi-Protocol Storage Switch acted as the iSCSI target device. The McDATA switch connected the incoming iSCSI traffic from the iSCSI server to a LSI ProFibre 4000 Fibre Channel RAID subsystem. The LSI RAID storage included high-performance 15K RPM disk drives from Seagate.

Traffic Generation

Iometer, a server performance analysis tool developed by Intel, drove traffic for the tests. The server was running an iSCSI/TCP/IP session across the Gigabit Ethernet link. Version 2003.12.16 was used in the configuration. For more information on how Iometer was used during these performance tests, see Appendix A: Iometer Information.