Tuesday, 13 June 2006

Oversubscribed and undersupported

Been thinking about oversubscription and port usage. I suspect most SANs are seriously underutilising their available bandwidth. Oversubscription is therefore a good thing - but it will be dependent on being able to use that oversubscription. Cisco switches (gen2) allow oversubscription at the port group level. On a 48-port card this is per group of 12 ports but there are restrictions - try putting more than two 4Gb/s ports at dedicated in a port group and you'll have to start turning other ports off! Restricting per port group is not enough. McDATA restrict by 32 port blade - fine, but the blades run at 2Gb/s unrestricted anyway. Brocade - not restricted - am I paying for bandwidth I don't need? Give me lots of ports and a reasonable amount of bandwidth for my money - and let me share it everywhere.

Why does EMC not support ECC on VMware? OK, I guess the Repository and Server components may cause a problem, but the stores - surely they can. What is going on with EMC and acquisitions? I can't believe it can integrate all of the software from the companies recently purchased - come on, at least ECC on VMware please - they're both your products.

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