multi-writer option and RDM

[khaled1111]

Hello,

What is difference between using shared hard disk  with "multi-writter" option between multiple VMs and "Raw device mapping", where that VMs are cluster.

Thanks

[UmeshAhuja]

Hi,

The multi-writer option allows VMFS-backed disks to be shared by multiple  virtual machines. This option is used to support VMware fault tolerance, which  allows a primary virtual machine and a standby virtual machine to simultaneously  access a .vmdk file.

Raw device mapping allows a special file in a VMFS volume to act as a proxy for a raw device. The mapping file contains metadata used to manage and redirect disk accesses to the physical device. The mapping file gives you some of the advantages of a virtual disk in the VMFS file system, while keeping some advantages of direct access to physical device characteristics

[khaled1111]

Thank you UmeshAhuja , and i want to ask , which is perefered between these?

[UmeshAhuja]

Hi,

According to me I think physical disk has the obvious advantage because you can directly access it with  any server that can be connected to it, while a virtual one needs an operational  virtualization layer to be accessed.

The performance difference between the two options is really negligible

[khaled1111]

Thank you very much

[UmeshAhuja · Accepted solution]

Awarding the points will be appreciated