> Why iSCSI


Posted on Thursday, November 08, 2007 | No Comments

I really should blog more. Oh well.

Its hard to have a conversation these days without someone trying to convince me that Fiber Channel is dead and iSCSI is where it is at. Whilst I agree with this in the long term I don't see it in the short term. Sure anyone can get iSCSI working in a lab hacking a few free things together, but thats not comparing apples with apples. You need to compare deploying iSCSI in a best practice environment to a FC one.

Here is my current argument, email me if you think I am wrong or have missed something.

  • Fiber Channel switch costs. If you only have two hosts, which can be common in a VMware environment, you can get away with no FC switches. Just connect each port of dual dual HBA to each storage processor on you SAN. If you have more than two hosts then you are going to need some FC switches, say $3.5K each. If you are following best practices for your iSCSI you would have a separate switching infrastructure for the storage, these are going to cost you about the same. Let alone what a 10G switch will cost.
  • HBA cards. Well a dual port HBA card is going to cost you about $2K. Two high end network cards with TOE are going to cost you about $1.6K, thats not a great saving.
  • A lot of the arguments are based on 10G Ethernet. People are not already running this so they are going to have to go out and purchase bleeding edge switches and cards compared the now commodity fiber channel equivalents.
Now there are lots of other elements to consider but for the big ticket items for the size of installations I see (two to ten servers running VMware) the cost difference is not drop dead argument of iSCSI is so much cheaper than FC.

If it was not for VMware I think FC would be dead a lot sooner than it otherwise would have been, its still got some legs for a while.

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