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Fabrics with different speeds
Hello all helpful folks,
We are planning to build a SAN island at our shop and are trying to gather swiches from wherever we can. We cant buy a new one. We have one switch which has maximum speed of 2gbps and another switch at 4gbps.
i) Can we build two fabrics using these two switches, knowing that they will operate at different speeds?.
ii) What will be the impact to the host or the array if we do this?.
iii) What will be the impact to the host based load balancing, if any?
iv ) Should we force the speed of the 4gbps switch to 2gbps or does it not matter because they are independent fabrics?
Thanks a bunch!
lee6
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March 10th, 2011 17:00
So you are looking to have fabric A and fabric B.
Sorry to say but if you have servers connected to the fabric and the fabric switch to a SAN or SAN's the MPIO will chose the fastest and that will be 4GB.
You will need to look at you server HBA cards and see what they can do and what the PFS's on the fabric swich can do.
You may be able to force a 2 GB speed if your HBA's and PFS's and switch will let you.
Donot for get to have the most current firmware on the HBA's and on the switches.
RRR
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5.7K Posts
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March 11th, 2011 02:00
You only have 2 switches ? If your SAN was any bigger, you could have 2Gb switches on each side for low speed server connections, allowing other servers to use the 4Gb switches and some servers on the 2Gb edge switches. these edges can be ISL'd to the 4Gb switches (always use at least 2 ISLs for redundancy and load balancing).
But if each fabric only consists out of 1 switch it's hard to properly use all available bandwidth, since Powerpath as well as MPIO will preferably use the fastest path only....