vsphere-esxi-vcenter-server-55-storage-guide

Chapter 10 Using ESXi with iSCSI SANThe 16-hexadecimal digits are text representations of a 64-bit number of an IEEE EUI (extended uniqueidentifier) format. The top 24 bits are a company ID that IEEE registers with a particular company. Thelower 40 bits are assigned by the entity holding that company ID and must be unique.iSCSI InitiatorsTo access iSCSI targets, your host uses iSCSI initiators. The initiators transport SCSI requests and responses,encapsulated into the iSCSI protocol, between the host and the iSCSI target.Your host supports different types of initiators.For information on configuring and using iSCSI adapters, see Chapter 11, “Configuring iSCSI Adapters andStorage,” on page 75.Software iSCSI AdapterA software iSCSI adapter is a VMware code built into the VMkernel. It allows your host to connect to theiSCSI storage device through standard network adapters. The software iSCSI adapter handles iSCSIprocessing while communicating with the network adapter. With the software iSCSI adapter, you can useiSCSI technology without purchasing specialized hardware.Hardware iSCSI AdapterA hardware iSCSI adapter is a third-party adapter that offloads iSCSI and network processing from yourhost. Hardware iSCSI adapters are divided into categories.Dependent HardwareiSCSI AdapterIndependent HardwareiSCSI AdapterDepends on VMware networking, and iSCSI configuration and managementinterfaces provided by VMware.This type of adapter can be a card that presents a standard network adapterand iSCSI offload functionality for the same port. The iSCSI offloadfunctionality depends on the host's network configuration to obtain the IP,MAC, and other parameters used for iSCSI sessions. An example of adependent adapter is the iSCSI licensed Broadcom 5709 NIC.Implements its own networking and iSCSI configuration and managementinterfaces.An example of an independent hardware iSCSI adapter is a card that eitherpresents only iSCSI offload functionality or iSCSI offload functionality andstandard NIC functionality. The iSCSI offload functionality has independentconfiguration management that assigns the IP, MAC, and other parametersused for the iSCSI sessions. An example of a independent adapter is theQLogic QLA4052 adapter.Hardware iSCSI adapters might need to be licensed. Otherwise, they will not appear in the client or vSphereCLI. Contact your vendor for licensing information.Establishing iSCSI ConnectionsIn the ESXi context, the term target identifies a single storage unit that your host can access. The termsstorage device and LUN describe a logical volume that represents storage space on a target. Typically, theterms device and LUN, in the ESXi context, mean a SCSI volume presented to your host from a storagetarget and available for formatting.Different iSCSI storage vendors present storage to servers in different ways. Some vendors present multipleLUNs on a single target, while others present multiple targets with one LUN each. While the way thestorage is used by ESXi is similar, the way the information is presented through administrative tools isdifferent.VMware, Inc. 71