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Is it a good idea to use both the ports of a FA in same port group?
Customer is having VMAX 10K(code 5876) with 2 engines and 32 FA ports on whole. Is it a good idea to use both the ports (0 & 1) of FA directors in same port group? For instance, I want to create a port group for a ESXi cluster with 24 hosts and use eight FA ports like: 1E [0 & 1], 2E [0 & 1] 3E [0 & 1], 4E [0 & 1]. The old directors are running on Fabric A and Even directors are running on Fabric B. The port group will still have good redundancy as it is running through, 2 Engines and 4 directors. I think we can analysis the performance easily on Unisphere under Real Time and Diagnostic. Any thoughts?
Quincy561
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July 12th, 2013 14:00
Because there is absolutely no performance to be gained, only lost. Both ports share the same CPU. Sometimes sharing the CPU with the same devices on two ports will cause a slight performance degradation.
pete2c
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July 12th, 2013 13:00
We've seen issues in the past with hosts being attached to both ports on the same FA. Specifically with Microsoft clusters, it can cause issues with scsi reservations.
Quincy561
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July 12th, 2013 13:00
You should never attach the same device to both ports of one FA CPU, IMHO.
pete2c
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July 12th, 2013 14:00
My comment was based specifically on an issue I saw with Microsoft Clusters. If you plan to cluster Windows VMs on your ESX hosts, be aware of this. Also I agree generally it's not a good idea.
For some additional info see the link below.
https://emc--c.na5.visual.force.com/apex/KB_BreakFix_1?id=kA1700000000IfG
If that link doesn’t work you can look up KB article 000058595 on https://support.emc.com
Quincy561
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July 12th, 2013 14:00
However if you can assign the 24 hosts in such a way that no LUNs share the ports on the CPUs, that is fine. It is the individual devices that shouldn't share the ports on the CPU, not the host.
Satya_kottur2
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July 12th, 2013 14:00
May I know your reasons for not assigning FA's this way? I want to do this for a ESXi farm.
dynamox
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July 15th, 2013 13:00
we have 1 port from even directory and 1 port from odd directory on fabric A and the same thing on fabric B.
Satya_kottur2
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July 15th, 2013 13:00
Make sense. Thanks for detailed explanation. I am planning for something like this:
Please give your suggestions.
Thanks
Quincy561
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July 15th, 2013 13:00
Looks reasonable. One other thing you may want to consider is looking at the workloads, and putting low and high demand workloads on the port 0 and 1 of the same CPU. Or not to put 2 high demand workloads on both ports of the same CPU if possible.
Satya_kottur2
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July 15th, 2013 14:00
Yes I am aware of workloads and paired the best possible ones. Thanks for your suggestions.