Wednesday, June 13, 2012

VMware RDMs in Physical Vs Virtual compatibility mode

VMware RDMs in Virtual compatibility mode
VMware RDMs in Physical compatibility mode
advanced file locking for data protection
No

Take Snapshots and snapshot based back up is possible
No

Behaves exactly like a virtual disk & Guest OS sees it as a virtual disk and the real characteristics are hidden.
RDM behaves as a virtual disk
Allows the Guest OS to access the hardware directly.
Luns with size limit of 2tb for RDMs
Luns of size greater than 2tb are supported
A disk device backed by a virtual compatibility mode raw disk mapping can use disk modes.
A disk device backed by a physical compatibility mode raw disk mapping cannot use disk modes, and commands are passed straight through to the LUN indicated by the raw disk mapping.
Doesn’t support MSCS (Microsoft clustering services)
Supports MSCS (Microsoft clustering services
For virtual compatibility mode RDMs, you can migrate the mapping file or convert to thick-provisioned or thin-provisioned disks during migration as long as the destination is not an NFS datastore. If you convert the mapping file, a new virtual disk is created and the contents of the mapped LUN are copied to this disk
For physical compatibility mode RDMs, you can migrate the mapping file only.
Bad for SAN aware applications.
Best for SAN aware applications.
Cloning is possible
No
Create templates of the VM with RDMs in virtual compatibility mode.
No
During migration you can either migrate the mapping file or copy the contents of the RDM lun into a virtual disk.
Can’t migrate if the migration involves the copying of the disk
No
Scsi Target based softwares & SAN Management agents
No
Physical server to Virtual Machine Clustering