In my sdetup, I'm using dual-port Chelsio 10G cards throughout my home lab (Chelsio T420-CR and a few T420-LL-CR's, the low latency version, specifically). FreeNAS 9.10.2U3 - soon to be 11RC - is on its own physical server and shares datasets and zvols on Samba and iSCSI respectively. The main iSCSI initiator is ESXi (ESXi 5.5 but upgrading to ESXi 6.0 or 6.5 if my Quadro 6000 + vSGA can unofficially still work on that version). The FreeNAS iSCSI target hosts the VM store, and the samba shares contain data files used by physical as well as VM LAN clients. The FreeNAS hardware spec is Supermicro + Xeon + 96GB 2400 ECC + Intel P3700 ZIL + 250GB NVMe L2ARC, and the ESXi server has an 8 core Xeon, 96GB ECC, and 250GB NVMe cache (both are specced to handle fast and large volume sync traffic as best I can figure out what's needed).
My question is, at the moment I'm newish to both ESXi and iSCSI, so I'm using ESXi's software iSCSI initiator. The T420 is described as having "Full iSCSI initiator and target mode stack" and "Full HBA offload" so it looks like they can be used to offload iSCSI from the CPU to the NIC on both boxes. If the Chelsio cards need a different driver, or a dedicated iSCSI NIC port or 2nd card for hardware offload, as a dedicated iSCSI target, then that's not a problem, I can do those things.
Is it worth setting up iSCSI offload on my FreeNAS box or should I carry on using the ordinary driver and iSCSI in software as I am presently doing (would I notice much difference and is Chelsio iSCSI offload firmware reliable)? If it's worth switching to hardware iSCSI offload (on just the target, just the initiator, or both), how do I make it happen (in FreeNAS and ESXi) and will it be easy to reverse back to non-offloaded sharing if I have issues?
My question is, at the moment I'm newish to both ESXi and iSCSI, so I'm using ESXi's software iSCSI initiator. The T420 is described as having "Full iSCSI initiator and target mode stack" and "Full HBA offload" so it looks like they can be used to offload iSCSI from the CPU to the NIC on both boxes. If the Chelsio cards need a different driver, or a dedicated iSCSI NIC port or 2nd card for hardware offload, as a dedicated iSCSI target, then that's not a problem, I can do those things.
Is it worth setting up iSCSI offload on my FreeNAS box or should I carry on using the ordinary driver and iSCSI in software as I am presently doing (would I notice much difference and is Chelsio iSCSI offload firmware reliable)? If it's worth switching to hardware iSCSI offload (on just the target, just the initiator, or both), how do I make it happen (in FreeNAS and ESXi) and will it be easy to reverse back to non-offloaded sharing if I have issues?
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