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I've got to buy a bunch of FC SAN switches in the next week or so, I have to, and want to, buy Cisco MDSs.

Servers are HP BL490c G6's in C7000 chassis with Virtual-Connect Flex-10 ethernet interconnects and VC FC interconnects (Emulex HBAs btw), all running ESX 3.5U4 (for now).

I think I've only really got two choices;

  • MDS 9509's with dual-supervisors with a single 48-port 4Gb FC card
  • MDS 9222i's with single supervisor and the built-in 18-FC-port/4-GigE-FCIP-port option

Both have the same functionality (I think, buying the enterprise licence btw), both have plenty enough performance and adequate ports for now and the next three years.

The 9222i's are about 55% the price of the 9509's - logic says get the 'i's but will I really miss the dual-supervisors? I've got lots of 9509's with dual-supervisors that I'm very happy with but I'm not sure I've every benefitted from the dual-sups in the past and they are nearly twice the price - but if I don't buy them and miss them I can't retrofit them later.

What are your thoughts?

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up vote 3 down vote accepted

For starters I would never use a dual supervisor FC switch as a replacement for having separate redundant pathways from your blade to your storage device. I would always use two separate switches. With that as a baseline I think it's all about comfort level. If you have a single supervisor and it fails in a switch, then your second switch will have to pick up the traffic. That is fine until you have two switches fail at the same time - you have to determine if the risk of that happening is worth the price for dual-supervisors. I would never want to answer that question for someone else, but I can say for our (small) shop we have single controllers and quick access to a spare switch so we never run with just one switch for long.

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Every machine has at least two paths to the storage, we're buying quite a few of these. –  Chopper3 Jul 16 '09 at 8:10
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