I have a esxi VM running CentOS 6.6. The previous SA had setup multipathing, but it doesn't make any sense for it to be used in a VM context since all the multipathing is handled by esxi.
Anyhow, im trying to present new luns to the VM and am getting the following errors. It's causing the host to hang when accessing the luns and not allowing me to rescan the bus or other lun related activity without hanging.

Jun 9 08:09:39 ssrxtstdb2 multipathd: sdm: get_state
Jun 9 08:09:39 host multipathd: sdm: state = running
Jun 9 08:09:39 host kernel: sd 4:0:1:0: timing out command, waited 30s
Jun 9 08:10:10 host kernel: sd 4:0:0:0: timing out command, waited 30s
Jun 9 08:10:10 host multipathd: sdm: state = 2
Jun 9 08:10:10 host multipathd: sdm: checker msg is "emc_clariion_checker: Read error for WWN 600601604630230078d54006a80ee511. Sense data are 0x0/0x0/0x0."
Jun 9 08:10:10 host multipathd: sdm - emc_clariion_checker: Read error for WWN 600601604630230078d54006a80ee511. Sense data are 0x0/0x0/0x0.
Jun 9 08:10:10 host multipathd: sdm: mask = 0x8

Is it possible to disable multipathing? Existing raw devices are already defined and in-use as /dev/mapper devices, so im worried that if I change the definition of the raw devices to point to the /dev/sd? equivalent, they will not be correct and that may corrupt the database running on those /dev/mapper luns.

The way I'm imagining this is set up, CentOS has two NICs connected to different VM portgroups. These portgroups are on separate vSwitches, with one or more uplinks to your SAN.

With that in mind, I would remove those NICs, and connect ESXi to that SAN directly, either with hardware or software based iSCSI connections - if not connected already. Once that is done, add the raw LUN's .vmdk mapping file as an extra drive to CentOS.

This way, CentOS sees it as a direct attached disk, and ESXi manages the connections.

Thanks. The LUNs are SAN based to the esxi host, then "Mapped RAW lun" to the CentOS VM. The VM only sees a single path for the lun.
I did find a way to disable multipathing, and was able to point the db raw devices directly to the /dev/sd? device names rather than the /dev/mapper/device names.