[Users] [node-devel] Help required to configure shared storage on RHEL+KVM

[Itamar Heim]

On 08/29/2012 12:34 PM, David Jaša wrote:
> (moving to users@, node-devel is definitely a wrong list but I'm not
> sure about a correct one)
>
> hi Amol,
>
> Sanglikar, Amol (Serviceguard) píše v Pá 24. 08. 2012 v 10:20 +0000:
>> Hi Ovirt dev-Community,
>>
>>
>>
>> We have a host running RHEL 6.2 + KVM , and created 2 Virtual machines
>> on the host which are running RHEL6.2.
>>
>>
>>
>> We are trying to configure shared storage for 2 VMs. This shared
>> storage on VMs should understand the SCSI requests.
>
> IIRC, if you need to pass through SCSI requests from the VM to the
> underlying block device, you need virtio-scsi qemu device that is
> included in RHEL as a tech-preview since 6.3 - again IIRC.

not sure this is about ovirt at all?
why not iscsi from guests to storage directly?

>
>>   The reason for this requirement is that we would be using SCSI-3 PR
>> (persistent reservation ) utils, which is sg3_utils to register /
>> reserve  on the storage/disks.
>>
>>
>>
>> We believe that exposing the raw LUNs from host to VMs as shared
>> storage (which is same as RDM - Raw Device Mapping in VMware ESX
>> environment )  would meet our above stated requirement.
>>
>>
>>
>> So can you please help us understand the following
>>
>>
>>
>> 1/  How to expose the Raw LUNs , from host ( RHEL 6.2 + KVM ) to
>> Virtual machines which are running RHEK 6.2.
>>
>
> You should create a shared disk but you can't get it really raw in terms
> of scsi commands unless you switch to virtio-scsi. It is raw in a sense
> of not using intermediate layers like qcow2 on top of the LUN.
>
> David
>
>> 2/  Also , if there is any alternate way to achieve the above
>> requirement in RHEL + KVM environment, apart from the mechanism we
>> stated , please let us know.