Adding passthrough disks as RDM on ESXi 6.x


In this example, the client had a need of accessing the disks directly, while sharing a LSI Megaraid controller which was on IT mode. This enabled the controller to have it’s own set of disks in an array, and also 6 disks with 4TB each that were needed as direct disks to the VM.

Start by configuring the desired disks as pass-through disks in the controller.

After enabling SSH on the host, connect to it and retrieve the disks available on the system by running the following:

ls -l /vmfs/devices/disks

Once you identify the disks, take note of their paths. If they are partitioned, take the shortest name by disk.

For more information on this, please check this KB on VMware

Run the following vmkfstools for creating a link between the disk and a VMDK pointer that’s residing within the same folder as the VM:

vmkfstools -z /vmfs/devices/disks/t10.ATA_____WDC_WD40EFRX2D68N32N0_________________________WD2DWCC7K6VNN944 "/vmfs/volumes/54e6da8d-a5249580-f600-0cc47ac1aeea/VM/WD_1.vmdk"

Go back to ESXi and map the WD_1.vmdk as an existing disk to the VM.

This will create a pointer to the disk, by using a dummy file “WD_1.vmdk” that actually points the VM to the disk directly.

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