HPE EVA Storage

Single SAN Switch at DR site with Continuous Access

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Ramaprasad K
Regular Advisor

Single SAN Switch at DR site with Continuous Access

Hi all,

There is a proposal.

We have Primary site with EVA and 2 SAN Switches, and DR site with EVA. We want the EVAs to mirror data using CA. But due to cost savings, we plan for a single Switch(though I am aware it doesn't cost much compared to EVA and other equipment) at DR.

I am of assumption that Technically and logically, there shouldn't be any Performance or availability issue due to Single switch with CA (when every equipment is working fine). I wanted to know if my assumption is correct?

Steven Clementi
Honored Contributor

Re: Single SAN Switch at DR site with Continuous Access

First question is... What model SAN Switches are being proposed?

Some issues you will have:

1. CA traffic will be limited to only 2 ports on either EVA, limiting host access at the dr site.

2. Non-redundant configuration at the dr site

3. Will the single link between the sites support your replication traffic?

Steven Clementi
HP Master ASE, Storage, Servers, and Clustering
MCSE (NT 4.0, W2K, W2K3)
VCP (ESX2, Vi3, vSphere4, vSphere5, vSphere 6.x)
NPP3 (Nutanix Platform Professional)
Ramaprasad K
Regular Advisor

Re: Single SAN Switch at DR site with Continuous Access

Thanks Stevan for the quick reply.

We are aware of all the 3 points and we know its not the best practice and we are ready for it.

I am specially interested in if any kind of Data inconsistancies would arise? Will CA work with the proposed setup without issues?

In fact, in case of Catostrophic disaster at Primary site, the DR is expected to work at 50% efficiency/availability of the primary.

Honored Contributor

Re: Single SAN Switch at DR site with Continuous Access

Hi Ramaprasad,

We manage a number of EVAs across our two sites (with CA replication) - based on this experience, a couple of points:

1. If you look at the cost of a SAN switch in the context of cost of multiple EVAs, CA license cost itself, etc, its not much! So, in all honesty, having multiple switches even at your DR site would provide an additional layer of redundancy + traffic load balancing.
2. Which EVAs do you have at your DR site - I don't have the exact details at the moment but some EVA models with certain XCS code had some issues with attaching all their controller host ports to the same SAN switch and required them to be spread across multiple SAN switches.
3. Apart from points 1 & 2, so long as the correct port routing, IOD fab parameters are in place - CA should work fine.

Let me know if you need more info.