ESX server 3 supports both hardware and software initiated iSCSI. For hardware iSCSI, we can use host bus adapters which perform the TCP offload and so the vmkernel can just pass SCSI commands to them as normal. The iSCSI hba can then wrap the SCSI command in IP transport and forward them to the iSCSI target.In VI-3, one of the supported iSCSI hardware HBAs is the QLogic 4052. More information about this particular family of adapters can be found at http://support.qlogic.com/support/product_resources.asp?id=964In software iSCSI initiator, the wrapping of SCSI commands in IP is performed by the VMkernel and a regular physical network card is used to communicate with the iSCSI target. The software iSCSI configuration is exposed in the VI Client as a host bus adapter called vmhba40 in ESX 3.0.x and is called vmhba32 in ESX 3.5. We can use this command line tool esxcfg-swiscsi to configure the software iSCSI initiator. The software iSCSI initiator in the VMkernel has a dependency upon the service console, therefore both the service console and VMkernel must have an IP route to the iSCSI target. The esxcfg-swiscsi command is not used in isolation, we use it in a sequence of commands to fully configure iSCSI from the service console command line.1. Add a VMkernel port to a vSwitch that has an uplink and route to iSCSI target

2. Ensure service console IP interface has a route to the same iSCSI target

3. Using either the VI Client security profile or the esxcfg-firewall, open a port in the service console firewall for iSCSI (TCP:3260)

4. In the command line, enable iSCSI with the command esxcfg-swiscsi -e

5. Enable a discovery address with the command vmkiscsi-tool -D -a 10.0.0.99 vmhba32

6. List the targets that were discovered with vmkiscsi-tool -T -l vmhba32

7. Perform a rescan with esxcfg-rescan vmhba32

8. List the iSCSI LUNs with vmkiscsi-tool -L -l vmhba32

If you want to ensure the VI client reflects the changes made at command line, it is best to restart the vmware management service with the command service mgmt-vmware restart

The full list of command line options for this command are:

-e, –enable Enable sw iscsi

-d, –disable Disable sw iscsi

-q, –query Check if sw iscsi is on/off

-s, –scan Scan for disk available through sw iscsi interface

-k, –kill Try to forcibly remove iscsi sw stack

-r, –restore Restore sw iscsi configuration from file (FOR INTERNAL USE ONLY)

-h, –help Show this message