vmware raw device mapping question

How to check raw device mapping using vSphere client? We have raw device mapping configured
and I need to find what are those devices. Please help.
mokkanAsked:
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mokkanAuthor Commented:
Also, I want to clear about the raw device mapping,  does it mean  it  mean it points to different device.
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coolsport00Commented:
What specifically are you wanting to check? A RDM is actually a "pointer" file for a VM. The file 'points' to storage on a SAN. In a VM -> Edit Settings, you see Raw-mapped disk (I believe is how it's worded). You add an RDM to a VM by 'Adding' a Hard Disk. You can find out more in the ESX Config Guide, Ch. 10 (pg. 123):
http://www.vmware.com/pdf/vsphere4/r40_u1/vsp_40_u1_esx_server_config.pdf

Regards,
~coolsport00
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coolsport00Commented:
So, for example, if you have a Windows OS for a VM, Windows sees the RDM as a volume in the OS. It's just another way to add storage to a VM if you don't want to add a VMDK Hard Disk from datastore storage.

~coolsport00
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mokkanAuthor Commented:
Thank you guys, I went to VM, edit setting and it is showing as raw-mapped disk, since we have many disks, how do I find where it is pointing to  since we have ns20, and other storage devices.
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mokkanAuthor Commented:
If I wan to add additional storage as raw device mappting, I need to create the  RDM file in ESX server. How do I create it? Do I need to create manually or I can do it through gui?
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mokkanAuthor Commented:
I have another question since VM pointig to storage directly. Do we need to install package or driver on VM?
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bbnp2006Commented:
You can add a RDM when you edit the properties of each VM, Edit virtual machine settings-->Add -> Hard disk, the 3rd option is Raw Device mapping.
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bbnp2006Commented:
and yes, because your windows virtual machine will treat this as a normal SAN device, so you will need the proper drivers inside your windows VM.
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bbnp2006Commented:
Here's a good read on How to configure rdm to use iscsi lun within a virtual machine using ms iscsi initiator.
http://www.experts-exchange.com/Software/VMWare/Q_24433850.html

Good luck!
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coolsport00Commented:
There is nothing further needed that you need to do besides adding a new "Hard Disk" in the Edit Settings area of a VM via the vSphere (or VI) Client. Again, the ESX Config Guide I provided explains more regarding RDMs. No drivers, etc. are needed.

Regards,
~coolsport00
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mokkanAuthor Commented:
Thank you all of you. I'm confused with bbnp2006 statement that I need the driver.  Storages are connected using  HBAs and ESX server has drivers for them and it is detecting the storage devices. Why do I need to worry about drivers, when I update patch on guest OS? It is a critcal box and I need to make sure I do patching.
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coolsport00Commented:
I'm actually confused as well! :P

Drivers to connect a SAN to your host are, as you mention, based off HBA device drivers needed in ESX. If your host 'sees' your storage adapters, you're golden. ESX should pass that storage through to your VMs. Your VMs will see that RDM storage as a volume and you initialize the disk/format as if the VM was a physical box (assuming it's a windows guest OS on your VM).

~coolsport00
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bbnp2006Commented:
Sorry for the wording guys coolsport is right :) as long as u have the right driver to asee the device from ur esx host, ur vm is simply adding it as a scsi device.  
My appologies for the confusion.
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mokkanAuthor Commented:
Thank you, it is a llinux box, when we create RDM using vsphere client  it will create RDM file  on host at /vmfs/volume/......, and then I should be able to see the disk using fdisk command from guest os right? For the patching I don't need to worry about anything since host is handling everything. Am I missing some thing here?
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coolsport00Commented:
Nope...you got it! :)
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mokkanAuthor Commented:
Thanks a lot for all of you.
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bbnp2006Commented:
Good luck with the configuration Mokkan!
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