ESXi Raw Device Mapping RDM

To configure a local device as an RDM disk:

  1. Open an SSH session to the ESXi host.
  2. Run this command to list the disks that are attached to the ESXi host:
    ls -l /vmfs/devices/disks
  3. From the list, identify the local device you want to configure as an RDM and copy the device name.
    Note: The device name is likely be prefixed with t10. and look similar to: t10.F405E46494C4540046F455B64787D285941707D203F45765
  4. To configure the device as an RDM and output the RDM pointer file to your chosen destination, run this command:
    vmkfstools -z /vmfs/devices/disks/diskname /vmfs/volumes/datastorename/vmfolder/vmname.vmdk

For example:

vmkfstools -z /vmfs/devices/disks/t10.F405E46494C4540046F455B64787D285941707D203F45765 /vmfs/volumes/Datastore2/localrdm1/localrdm1.vmdk

Test Jumbo Frames / MTU 9000


ping -M do -s 8972


ping -D -s 8184


ping -f -l 9000

Example results on Linux

If you’ve forgotten to enable jumbo frames/9k MTU on your client device you’re sending the ping from:

PING ( 8184 data bytes
ping: sendto: Message too long

If you have enabled jumbo frames on your client but not the destination (or a switch in between):

PING ( 8184 data bytes
Request timeout for icmp_seq 0

If you’ve done everything righ:

PING ( 8184 data bytes
8192 bytes from icmp_seq=0 ttl=128 time=0.714 ms