phlight wrote:
Second questionI know that the max size of a datastore in vsphere 4 is 2 TB if configured with 8 MB blocks. I'm not sure I understand this "If the RDM is larger than the maximum VMDK size of the datastore that hold the VM’s configuration file; performing a snapshot on the VM with an RDM will fail."
Does that mean the datastore that holds my Windows 2008 server with the 2 RDMs needs to have 8MB block size to allow for my 2 1.33 TB RDMs to be backed up? All my datastores are using 8MB block size.
To be able to take VMware snapshots of a raw LUN the "extra data" must be stored somewhere. Since the raw LUN is not read/writable by ESXi (which does not the filesystem of the RDM LUN) the snapshot data is stored on an ordinary VMFS datastore.
In theory a snapshot could grow to the whole size of the disk being snapshoted, say if we took a snapshot, then formated the drive and replaced with totally different data. To be able to handle that the snapshot file must be able to in theory grow to this size. This means the VMFS LUN where the snapshot data is stored must be able to hold such large files, i.e. be using a larger blocksize.
If all your datastore is using 8 MB then this is not an issue for you.
