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iSCSI Fuels Midrange Storage
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Performance Concerns
The most glaring weakness of iSCSI when compared with Fibre Channel is performance. Any way you look at it, 2G-bps Fibre Channel networks are going to be faster than Gigabit Ethernet solutions.
However, as we have seen in our tests of iSCSI-based products from Nishan Systems Inc. (iSCSI/Fibre Channel switch), Alacritech Inc. (HBA) and Cisco (router), iSCSI's performance—while inferior to Fibre Channel in raw speed benchmarks—is still very usable in the real world. iSCSI should work fine for workgroup-class e-mail servers, file servers and even some lightly accessed database servers. And performance may be a moot comparison point as 10 Gigabit Ethernet becomes available.
However, IT managers shouldn't use iSCSI over Fibre Channel in environments that require high throughput or that need to process large amounts of transactions per second (such as high-end databases).
TCP/IP-offloaded adapters from vendors including Alacritech and Emulex Corp. should also help boost the performance of iSCSI. More importantly, they should lower the amount of CPU resources eaten up by networking tasks, freeing up precious cycles for applications.
In addition, as storage management tools get more intelligent, iSCSI may allow IT managers to create truly distributed storage networks, where storage space is transparent to users and servers, and volume management and QOS are automated to ensure constant performance.
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