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    Raw Device Mappings

    What is raw device mapping?

    Raw device mapping is a feature where the virtual machine can directly access the storage devices such as SAN or DAS.

    With a VMware we will use vmdk pointer to provide the proxy facility to raw device.

    In a virtual environment some cases we may need to have a raw device mappings.

    Why we need raw device mapping?

    • To configure Microsoft failover cluster, we can configure raw device as shared storage.
    • When we are configuring Microsoft failover cluster with one node is running on as a VM & other node/s running as a physical.
    • To run some of the san management software(ex hitachi horcm)
    • To run some backup software on virtual machine, and needs to get storage level backup

    How to Configure?

    1. Here I have one vm which is prepared to mount raw device

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    1. Using new datastore adding procedure, we can see new lun which is provided from our shared storage(in my case im using windows iscsi server)

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    1. Go to add hardware wizard of virtual machine and select hard disk

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    1. Select “Raw Device Mappings”

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    1. Select the Raw device lun

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    1. We can select location for VMDK pointer(raw device mapping pointer)

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    1. There are two options
      1. Physical
      2. Virtual- In a virtual mode we can take the snapshots

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    1. With physical mode of the raw device, we cannot take snapshots.

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    1. We can see vmdk pointer which is used to proxy our raw lun in our datastore.

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    10 . With a virtual mode we can take the snapshots

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    1. If want we can change the multipathing policy as same as datastore

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