Hi Russel,
FCM4 Small and Medium drives run at PCIe G4 unlike the FCM3 S and Medium which run at PCIe Gen3. However, this is only interesting on platforms that can run PCIeG4 (at this time that is the FlashSystem 9500 in Virtualize, and a couple of ESS models) and on workloads where we were PCIe BW limited to the drives.
So while the individual PCIe BW to the drive has doubled, this does not equate to doubling performance at a system level, nor does it apply to most of our existing systems.
It does however, remove more potential bottlenecks and give us forward compatibility as more platforms move to Gen4.
As with all things in the world of performance, and in the words of Barry Whyte our former performance architect "It Depends".
I hope that helps.
Cheers,
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Evelyn Perez
IBM Senior Technical Staff Member
IBM Storage Virtualize Software Architect for SVC and FlashSystem
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