Powerpath and Symmetrix

Question

I've got a host with and HBA with two ports. A cable from each port connects to Cisco Switches, which then connect to a Symmetrix. When I open up PowerPath, how many paths should I be seeing for each disk? I know for a Clariion, I used to see four - Cable 1 goes to Switch 1, which goes to SPa and SPb, while Cable 2 goes to switch 2, which also goes to SPa and SPb, for a total of 4 paths. Would the same logic apply to a Symmetrix? Should I be seeing four?

Thanks

dynamox · Answer

How is it actually zoned ?

RRR · Answer

With Clariion it's a best practice to have 4 paths to your storage array (each HBA to SPA and SPB).
With Symm it's a best practice to have 1 path per HBA, so each HBA is connected to either TOP SAN (where the upper ports of the Symm are connected to) or BOTTOM SAN (where the lower ports of the Symm are connected to). Since each HBA can only connect to 1 edge switch, each HBA is automatically connected to 1 half of the Symm's ports. You could zone an HBA to more than 1 FA, but I'd only use that if an HBA is overloaded or something, so I/O's are spread over more FA's.

dynamox · Answer

hey RRR ..why are you calling your Symmetrix a SAN ?!?!? . There is somebody on this forum who gets really upset when you call storage array a SAN

RRR · Answer

TOP SAN are the switches that connect to the upper numbered ports of a SymmBOTTOM SAN are the switches that connect to the lower numbered ports of a SymmWill you now stop nagging ?

dynamox · Answer

hahaha ..you know i could not pass on that opportunity

Uwe-Ud0Mk · Answer

What type of 'SAN' do you have? Is it a Symmetrix SAN or a Clariion SAN? LOL.

RRR · Answer

Grrrrrrrrrrrr

NeilHopwood · Answer

Steven

A Symmetrix is (don't bite me here) more resilient than a Clariion on so you only need one HBA connected to one FA port of the Symm. You have two such paths via two HBAs for redundancy on the host side and also to improve performance.

The zoning we are discussing here is the logical connection from the HBA to the FA port. So in this example you will have two zones only.

There is nothing stopping you from adding extra FA port connections to the HBA via additional zones this then enables you to present more devices (via masking) to the host which, in the case of a system with many LUNS can slow boot times down significantly.

Bottom line is that it is a typical setup you are seeing - one HBA zoned to one FA port.

skong · Answer

All, thanks so much for your help. This helps explain things for me. I don't 100% trust our storage admin here and I wanted to make sure we were setup properly with best practices

Much appreciated,

S.

Allen Ward · Answer

I'm not sure which is riskier... dynamox and Uwe egging on RRR (for something that I agree fully with him about) or you commenting about not fully trusting a Storage Admin *lol*

Hopefully he doesn't have access to this forum too :-)

RRR · Answer

I wouldn't trust RRR or the storage admin, LOL

Symmetrix

Powerpath and Symmetrix

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