ESX "raw" disk

Version 5

    Introduction

    A "raw" disk is a storage disk (if could be a physical disk, but usual is a LUN or a storage logical disk) that will be connect "directly" to the VM.

    Usually VM disks are vmdk files that reside on a VMFS volumes on a storage disk.

    In this case the raw disk is not formatted with VMFS but is formatted with guest OS filesystem.

     

    With ESX there are different way to have a "raw" disk:

     

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    Raw disk pro and cons?

    VMFS vs RDM (vs VMDirectPath and other solutions)

    http://www.vmwareinfo.com/2009/03/deciding-between-rdms-or-ms-iscsi.html

     

    Extend a RDM disk

    RDM - unable to extend disk

     

    How to check if VM use RDM?

    A simple way is use RVTools.

    But also Perl or PowerShell scripts can be used:

    How to find the VM's connected to a partical RAW Map LUN.

     

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    RDM on local disk

    With the VIC or the vSphere client is possible create a RDM disk for SAN's LUN.

    To use local storage with RDM (for example to connect and existing NTFS volume) the vmkfstools must be used from the CLI:

    Re: question about RDM using local disk ESX 4

    http://itknowledgeexchange.techtarget.com/virtualization-pro/vmware-esx-storage-how-to-get-local-storage-to-act-as-a-raw-disk-for-vms/

     

    ESXi cannot use local disk RDM

    VMwareServer -> ESXi, Local Storage options? RDM?

     

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    Virtual disk performance

    VMFS vs RDM (vs VMDirectPath and other solutions)

    Performance Characterization of VMFS and RDM Using a SAN - http://www.vmware.com/files/pdf/performance_char_vmfs_rdm.pdf

    Thin vs Thick - http://www.vmware.com/pdf/vsp_4_thinprov_perf.pdf