NFS datastore vs Lun datastore

[netappmagic]

in NFS datastores, each virtual disk file has its own I/O queue directly managed by the NetApp FAS system.

in LUN datastores, it doesn’t natively allow a storage array to identify the I/O load generated by an individual VM.

Would you please explore these two statements more? I could not fully understand them. In NFS, please explain to me in detail or by example on how I/O queue directly managed by a filer.

Why in LUN datastores the filer cann't identify the I/O load?

Also, in a "best practice" document, it says that virtual disks could be connected to all nodes in the clustter but is only accessed by a single VM, i thought it could be shared which means it could be access by multiple VM's.

Thanks for your inputs.

[johannbell]

With an NFS datastore, each VM is a file (a few files) which the Filer hosts. With a LUN, it all appears as a single file to the filer, regardless of how many VMs are in the LUN.

All ESX cluster hosts can see each datastore and therefore every VM. I think you may be confusing virtual disks and datastores.

[netappmagic]

These two statements were excerpted from TR-3749

but, why in NFS i can see those VM file's but in LUN, I can only see them all as a file? please explore it a little bit more. Thanks!