With Emulex driver version 12.8.534.0, Broadcom introduced a feature that makes the vVol Protocol Endpoint (PE) queue depth limit 254 by default in ESXi. This improvement is discussed in great detail in this whitepaper.
An issue was noticed in this driver version that could cause significant performance issues to vVol VMs hosted on the same ESXi host as vVol VMs whose volumes were being throttled because of QoS on a Pure Storage FlashArray™ product. If a single vVol volume is being throttled by QoS Rate Limiting or QoS Fairness on the FlashArray™ product, the SCSI commands sent to the ESXi host from the FlashArray™ product will cause the host's PE queue depth limit to be set as low as 32 and not return above that until the host is restarted. There are two issues here:
- All vVol volumes on an ESXi host being punished by a single vVol volume's QoS on the FlashArray™ product. This issue is resolved and the fix is in 14.0.326.12 and higher.
- A PE queue depth limit throttled down to 32 by this mechanism will not be able to adjust above 32 until the host has been restarted. This issue is being investigated by VMware.
Pure Storage has noticed the resolved issue on the included lpfc version of ESXi 7.0 U3, 126.96.36.199-5vmw, and recommends vVol customers who have upgraded ESXi to 7.0 U3 to upgrade to lpfc version 14.0.326.12 if their Fibre Channel HBA uses this driver.
Pure Storage recommends using the lpfc driver version 14.0.326.12 or higher.
This can be downloaded from VMware here.