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Will 4GB Pass Thru do 8GB?

Trusted Contributor

Will 4GB Pass Thru do 8GB?

Steve had a question regarding Pass-Thru modules:




The only pass-thru interconnect that I see is for 4GB. Will it do 8GB as well? The documentation is conflicting…..





Walton replied:

The Fibre Channel pass-through module is 4 Gb only.  Please point out where documentation is conflicting.


There is no 8 Gb FC pass-through. Such a module would cost as much as a switch due to the signal speeds involved and the necessity to comply with the expanded FC specification. With the need for 16 SFPs, the total cost would actually be more than a switch. It seemed pointless to undertake development of such an expensive product.


Input from Hitch:

To my knowledge, 4GB Pass through does work with 8GB components & infrastructure.


And a comment from Walton:

Steve clearly asked  “Will it do 8GB as well?”  To that, the answer is NO because the 4 Gb FC pass-through is capable of one speed – 4 Gb.


If he had asked “Will it work with 8 Gb infrastructure?” I would have said “YES, if you allow the FC Mezz card to run at 4 Gb/sec and accept that 4 Gb external ports are OK”




Any other comments?



Robert Cook_6
Frequent Advisor

Re: Will 4GB Pass Thru do 8GB?

The g9 blades are shipping with the QMH2672 FC card which does not go down to 4GB.  I have 7 c7000 enclosures with the 4GB Pass Thru modules.  Has anyone else faced this problem? 

Any sufficiently advanced technology is indistinguishable from magic. Arthor C Clark