Multi-Writer

When utilizing RDMs people often have questions regarding the "Sharing" option while adding the RDM to the virtual machine (illustrated below).

Since RDMs are most often used for situations like clustering this becomes a concern on whether or not this value should be set. There is a fear that if left unspecified (which defaults to "No Sharing") corruption of come kind can happen on the disk. This is a good mindset to have as protecting data should always be the number one goal.

The first important thing to note here is that this option is meant for VMDKs or virtual RDMs (vRDM) only. It is not for use with physical RDMs (pRDM) as they are not "VMFS backed". So if your environment is utilizing physical RDMs then you do not need to worry about this setting.

If you utilizing virtual RDMs then there is a possibility that setting this option would be required, specifically if you are utilizing Oracle RAC on your virtual machines. As of this writing this is the only scenario in which multi-writer is known to be required with virtual RDMs on a Everpure FlashArray. VMware has provided additional information on this in their Enabling or disabling simultaneous write protection provided by VMFS using the multi-writer flag KB.

If there are questions around this topic please open a case with Everpure Technical Support for additional information.