Hello, we are setting up a new Storage Infrastructure and need to chose the connectivity type for mail servers: iSCSI or fiber channel.
Does anybody have any recommendation / experience with one of these? Anything to say about performance, reliability, any problems encountered?
Thanks & regards,
Marie-Noëlle
Subject: ISCSI versus Fiber Channel
In our environment we chose fiber channel because it offers better performance. We have an IBM BladeCenter running 5 HS20 blades (dual 3.6Ghz Xeon, 4 or 8 GB RAM), 2 dedicated for Domino, and the other 3 are running VMWare ESX with a total of 11 Windows and Linux partitions. This connects to an IBM DS4300 SAN with 14 x 73GB 10K RPM drives.
At the heart of the issue is a fundamental design difference: fiber channel is designed to handle high volume block level I/O; ethernet is not. Entry level fiber channel is 2Gbps, 4Gbps is pretty widely available, and you can go as high as 10Gbps if you need it. To the best of my knowledge ISCSI runs at 1GBPS, period, unless you get into some extremely esoteric implementations that use 10G Ethernet. With ISCSI you can implement multipath IO and use multiple adapters, but that gets expensive in a hurry and negates the cost savings of using ISCSI to begin with.
In a different environment where I wasn’t booting multiple OS’s from a SAN and was basically using the SAN as bulk storage I would probably have considered ISCSI more. With what we’re doing, though, it was pretty quickly ruled out.
HTH,
Charles