In response to this article, "HOW TO: Add Local Storage (e.g. a SATA disk) as a Raw Disk Mapping (RDM) or Mapped RAW LUN to a virtual machine hosted on ESXi"
, I have several questions about utilizing RDM for my deployment. I am attempting to utilize a RAID volume that is larger than 2TB within my datastore and was hoping that RDM would be a stable enough solution. I am running ESXi 5.0 while following the mentioned article and have run into an error.
In step 3 of the guide, "Using the vmkfstools command to create the RDM", I am getting an error when I attempt to run the command to provision the RAID volume. I have located my RAID volume and assembled my command, but I am receiving the following error with the accompanying debug info:
# vmkfstools -r /vmfs/devices/disks/naa.XX
DISKLIB-LIB : CREATE: "/vmfs/volumes/datastore1/
k" -- vmfsRawDeviceMap capacity=0 (0 bytes) adapter=buslogic devicePath='/vmfs/devices/
DISKLIB-LIB : Only disks up to 2TB-512 are supported for 'vmfsRawDeviceMap' disk.
Failed to create virtual disk: The destination file system does not support large files (12).
In the head of this article, it is stated:
There is a limitation in VMware Hypervsior ESXi 4.x of a 2TB VMFS datastore limit, this can be overcome by using RDMs.
It has been also been stated that this limitation has been removed as of ESXi 5.0. Is there a necessary step to allow partitions greater than 2TB to be created as RDM disks? I was under the impression the change from MBR to GPT was what allowed this functionality, but I am not certain as to what that will require. For your 500GB drive there was no additional preparation, but to overcome the 2TB limitation, is there another step that I need to complete prior to running the vmkfstools command? Possibly creating a GUID Partition table for the drive?
Also, is there a way to use the remaining space on the installation drive for an RDM? For instance, with a large RAID 5 volume with ESX installed on it, the remaining space is partitioned automatically. Is it possible to use the remaining space as an RDM with a size of > 2TB within my datastore?