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Multi-Array Connectivity

Historically we have tried to maintain a SAN connectivity standard of a single OS instance only connecting to a single array. Originally that translated into one array per physical server, but with server virtualization that changed to allow the physical server chassis to connect to more than one array. We did require separate HBA ports for each array connection though. So if and ESX server needed to connect to a VMAX array it would have two HBA ports (one per fabric) and if it then needed to connect to a VNX as well it would have two more ports connected up.

There are lots of reasons for this and I'm not sure any more how many of them are still valid as technology progresses. There was a time when the absolute ideal HBA settings, drivers, or firmware may not be exactly the same between different array types. There are also the potential issues you could run into if a VM is provisioned off multiple arrays (accidentally) and one of those arrays has issues. There are other things that I'm not going to go into right here and now.

What I'm looking for is a sense from other people of what they are doing? Specifically:

  1. Do you allow a host to connect to multiple arrays?
  2. If so, do you use the same HBA ports or separate physical ports?
  3. Are there any established Best Practices out there that I'm missing that relate to this train of thought?

Thanks in advance for sharing!

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Re: Multi-Array Connectivity

Allen Ward wrote:

What I'm looking for is a sense from other people of what they are doing? Specifically:

  1. Do you allow a host to connect to multiple arrays?
  2. If so, do you use the same HBA ports or separate physical ports?
  3. Are there any established Best Practices out there that I'm missing that relate to this train of thought?

Thanks in advance for sharing!

1) Yes, i have hosts that connect to XtremIO and VNX at the same time.

2) Same HBAs being used for both arrays

3) Not sure if you have seen this discussion

jermo15
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Re: Multi-Array Connectivity

1. Yes Multi Arrays / Multi Vendor / same HBA Port(s).-

2. Using Host Connectivity Guide and Best Practice settings (like increase of Buffer)

3. "Fan-In/Fan-Out" for Single Ports is (or was) Part of the Product guide for each Array, (Fan in/out for Vmax: emc239025)

https://community.emc.com/message/501770

P.S. As you load more (Workload/Query) on the ports the "Overhead" increases, with More Fanning - the increase in Overhead is more pronounced by a factor of the Arrays involved.

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