This one is taken from the first objective in the VMware Enterprise Admin Exam Blueprint. Specifically from the skills section:
– Perform advanced multi-pathing configuration
— Configure multi-pathing policy
— Configure round-robin behavior using command-line tools
After logging into the host via SSH, and getting to root, this can be done with the “esxcfg-mpath” command. Let’s take a look at this command:
[root@ProfessionalVMware root]# esxcfg-mpath
esxcfg-mpath <options> [–lun=<LUN>] [–path=<path>]
-l|–list List all LUNs and their paths.
-p|–policy <type> Set the policy for a specific LUN. Requires
a –lun flag. Type must be one of mru, rr, fixed or custom.
-H|–custom-hba-policy Set the custom HBA policy value. Must be one of
mru, preferred, any, minq.
-T|–custom-target-policy Set the custom target policy value. Must be one of
mru, preferred, any
-C|–custom-max-commands Set the custom policy value for max commands
-B|–custom-max-blocks Set the custom policy value for max blocks
-s|–state <on|off> Set the state for a specific LUN Path. Requires
both –lun and –path flags.
-f|–preferred Set the given path to be preferred for the
given LUN. Requires both –path and –lun flags.
-q|–query Query the information on a specific LUN.
Requires a –lun flag.
-P|–path=vmhbaX:X:X Used to specify a path for setting the
path state or preferred path. Uses the
VMkernel internal path name.
-L|–lun=vmhbaX:X:X Indicate which LUN to operate on. This can be
either the internal VMkernel vmhba name for
this LUN (vmhbaX:X:X) or the vml name as
found in /vmfs/devices/disks.
-v|–verbose Show all information about the LUNs and
paths, otherwise a minimal set of data
is displayed to conserve space.
-b|–bulk Bulk path listing suitable for parsing.
-a|–hbas List HBAs on the system with a unique ID
if one is available.
-h|–help Show this message.
-r|–restore Restore path setting to configured values
on system start. (INTERNAL USE ONLY)
Quite the command, isn’t it? And that is but half the output. The particular switches we are interested in are –p or –policy to which we’ll feed the “rr” or round robin switch. We’ll follow that up with the –L or –lun to specify which lun we’re operating on. Here’s an example:
[root@ProfessionalVMware root]# esxcfg-vmhbadevs
[root@ProfessionalVMware root]# esxcfg-mpath –policy=rr –lun=vmhba0:0:0
Setting vmhba0:0:0 policy to rr
In all practical terms, on my lab box that didn’t accomplish much, as there is only one actual path to the disk, however, we can still see the changes in the VI Client:
Note: esxcfg-mpath is not actually listed in the tools section for this objective, but is indeed the way to accomplish this.