iSCSI works fully stable on ProLiant Gen9 servers (Windows Server 2012R2/2016 tested).
Time flies, but Moore's law still a law. Processor speeds continue to increase. For example, there is no need to offload the clock function from our mobile phones to separate dedicated hardware because the impact to phone performance is very low - yet first Nokia mobile phones were without the clock at all, because that required separate clock HW.
Similar is happening with iSCSI. There are no longer much benefits to offload the protocols to dedicated HW on NIC, even at 10Gbps speeds. Most NIC manufacturers no longer support stateful HW offloads, because iSCSI can just be used on any quality network card with software only initiator (built into OS), utilizing stateless accelerations on NIC, but via standard TCP stack. Why increase complexity with extra technology/drivers on server if everything works well without it, by just buying a few more cores in server processor or faster processor, and also because even encryption used for iSCSI is now accelerated in the processors. No surprise, that Intel explained already in 2010 why they will not implement iSCSI HW offloads in their NICs.
The last remaining card from HP that supports full iSCSI hardware offload on Gen9 servers is Emulex based HPE FlexFabric 10Gb 2-port 556FLR-SFP+ Adapter.
Check the description in standard features for "Hardware iSCSI or FCoE with Full Offload": The 556FLR-SFP+ is the only network option for HPE Gen9 rack servers that supports hardware FCoE or iSCSI with full protocol offload.
Emulex has the proven high quality offload drivers and works stable with offloads (Windows OS work stable starting from 2018-R2 version, I not tested if VMWare works properly). So inserting 556FLR into Gen9 server is the last chance to save on server processor utilization by TCP and iSCSI HW offload technologies.
Therefore, if you own G7/G8/Gen9 HP server today, have 10Gbps Emulex adapter, and access disks via iSCSI, or just use long data transmissions at very high bitrates with just a few TCP sessions (this is not for short TCP sessions like serving www pages), you can turn offloads on in Windows: for TCP, check this post, for iSCSI offload - you select the offloaded/HW initiator in GUI of OS "iSCSI initiator" program.
As situation develops now, it seems general processor speed increase is winning over HW offload technologies, as massively tested OS TCP stacks work well with most NICs, but for TCP/iSCSI offload you need high quality/stable offload drivers from high quality NIC vendor - currently only Emulex delivers it for HP ProLiant's, via 556FLR supported NIC card, in FLR form factor for inserting into special networking slot on Gen9.
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