8–Configuring FCoE in a Linux EnvironmentN_Port ID VirtualizationFE0254601-00 A 8-23Queue Depth (qla2xmaxqdepth)The Queue Depth parameter specifies the maximum number of SCSI commandbuffers that an adapter port can allocate. This parameter determines themaximum number of outstanding commands that can execute on any one adapterport.The default for the Queue Depth parameter is 32, which provides the bestperformance for most environments. The following factors may require anadjustment to the Queue Depth parameter to obtain the best performance: Total number of LUNs exposed through the storage array (target) ports Queue depth of the storage array portThe effects of changing the Queue Depth parameter are most evident when theapplication workload type is transactional (small block size I/O).N_Port ID VirtualizationN_Port ID Virtualization (NPIV) is a Fibre Channel facility that allows multipleN_Port IDs to share a single physical N_Port. N_Port sharing allows multiple FibreChannel initiators to use a single physical port, easing hardware requirements inSAN design, especially where virtual SANs are used. NPIV is defined by theTechnical Committee T11 within the INCITS standards body by the FC-DA (FibreChannel Direct Attach) and FC-LS (Fibre Channel Link Services) specifications.NPIV virtualizes the Fibre Channel adapter function such that each VM running ona server can share a pool of adapters, and maintain independent access to itsown protected storage. This sharing enables administrators to leverage standardSAN management tools and best practices, such as fabric zoning and LUNmapping/masking, and it enables the full use of fabric-based quality-of-serviceand accounting capabilities. Adapter sharing also provides the most efficient useof the adapters in the server, while ensuring the highest level of data protection.NPIV allows a single, physical, Fibre Channel adapter port to function as multiplelogical ports, each with its WWPN, as shown in Figure 8-9.
