Migrating Virtual Machines from VMFS to RDM's

[Auz]

Hi All,

I am using VMware ESX 3.5 servers and Virtual Centre 2.5 U3, I am looking to migrate all my Virtual Servers to use RDM's as we are currently using VMFS with a HP EVA 8100 with CA. I have had a look over the net and can not find much information the this topic. Can this be done? If so is it supported by VMware? The reason for us doing this is so it provides us much more resiliency in DR and will help us to have high availability.

So basically is there a simple way of moving a virtual machine files and disk from using VMFS and convert it too RDM. I notice on the migration wizard there is no option to select a RDM drive.

Any information would be appreciated.

Thanks

Austin

[mike_laspina]

Hi,

It's interesting that you consider an RDM to be more available than a vmdk. I consider it to be the other way around as vmdk's are a virtualized storage unit and have some interesting and flexible options when it comes to availability. I have a blog on some of these ideas. Regardless of that I know of thre methods you can use to convert them

1 - VMware Converter

2 - Mirror the volumes in the OS

3 - Backup and Restore e.g Veeam

Regards

Mike

[Auz]

Hi Mike,

Thanks for the reply, The reason we want to do this is because we want to fail over VM Servers individually. They way I have my Virtual Centre setup is at present we have: VMFS01, VMFS02 ,VMFS03 and so on. These VMFS volumes are shared between a large group of machines. This issue is in a DR scenario we want to have the function of individually failover certain machines without having to failover an entire VMFS Volume which contains several VM's. From Articles I have read and the technology we have I believe the best was forward is to use RDM's. One of the major reason for us to use RDM's is the factor we can resize volumes easier as you can not extend VMFS volumes. I know you can use extents but I dont really like using them if i have too.

If you can provide me with some comments which may sway me it would be welcome.

Thanks again

Austin

[mike_laspina]

Well there is merit in both methods, what I consider in the architectural formula is the future of virtualized systems and storage. In other words lets say you were to replace the backing store from an EMC to SUN or Netapp or whatever.

So how are you going to migrate the VM's that have RDM storage? It's time consuming and has more risk elements.

But if your VM has virtual disk backing like NFS and vmdks or VMFS and vmdk's you can migrate the VM from one storage archtecture to another without any service outage.

If your in a DR state you would certainly want all the essential VM's to be accessible ot the DR site and fail over is simply met by a power on cycle. If you have VM's that are not desired in the DR cycle them place them on stores that are not inluded in the replicated LUN model.

Regards

Mike