Hello

The answers are different depending if you are using vRDMs or pRDMs. pRDMs are not supported therefore are not included into backup.

If your questions are related to vRDMs answers are below.

Consider single VM with RDM will it be  possible to take  VM level backup of individual disk (scsi 0:0) alone in DP? Yes you can

Consider cluster VM (Active passive) with RDMs will it be  possible to take  VM level backup of individual disk (scsi 0:0) alone in DP? Yes you can

Consider cluster VM (Active/Active)with shared RDMs will it be  possible to take  VM level backup of individual disk (scsi 0:0) alone in DP? Yes you can

So basically if the VCenter is able to do the snapshot DP will use it, so limitations for vRDMs are:

• vRDM disks can be used only for full backups.
• Restore of virtual machines which have virtual RDM disks, to different vCenters is not supported.

Best Regards

  Thanks for your reply . Help me whether below my understanding is correct or not ? Thansk in advance Will ask further questions based on reply 

Consider a VM backup spec with one VM scsi 0:0 alone selected . Part of backup flow

First ----- It will take entire VM snap 

Second --- it will refer the backup spec and exclude all other scsi apart from  Scsi 0:0

Third -- Will  check Changed Blocks for disk 'scsi0:0' and start the backup 

Hello

Everything is right, so if your MV has more than one disk be sure that you just select the vRDM disk SCSI0:0 during backup creation.

Best Regards

  Thanks again for your reply .

1 . )  In Below scenario 

Consider cluster VM (Active/Active)with shared RDMs will it be  possible to take  VM level backup of individual disk (scsi 0:0) alone in DP? Yes you can

Part of Backup flow --In the first stage VM snap shot will be created for entire VM . When snap shot created it will lock the shared disk to a server  and  the shared disk will not be available for other server in cluster.  will it not cause any issue  while take VM backup of individual scsi in active active cluster ?

2. ) if a VM have both VRDM and PRDM will it allow us to take backup of individual scsi 0:0 (OS drive -- mostly provided from data store) ) ?  

Thanks in advance!!!

Part of Backup flow --In the first stage VM snap shot will be created for entire VM . When snap shot created it will lock the shared disk to a server  and  the shared disk will not be available for other server in cluster.  will it not cause any issue  while take VM backup of individual scsi in active active cluster ?

Snapshot is done from Vcenter not from DP, so if Vcenter is able to do it DP will use it. Can you run an snapshot for vRDM runing in active\active from Vcenter point of view? So if Im not wrong snapshots for VMs with disks engaged in SCSI bus sharing are not supported by VMware, so it will not be possible to backup these VMs with any VM-image level backup solution using sharing BUS.

 if a VM have both VRDM and PRDM will it allow us to take backup of individual scsi 0:0 (OS drive -- mostly provided from data store) ) ?

You can select which disks are included into backup specification and which not.

Best Regards