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

[Itamar Heim]

On 09/06/2012 09:47 AM, Sanglikar, Amol (Serviceguard) wrote:
> Hi All,
>
> Thanks for all your responses.
>
> 1/ we are using FC setup and not iSCSI. SO using SCSI is not an option for us right now.
> 2/ Yes you are correct NPIV will give us VHBA , but is it supported on guests as of now , both in case of RHEL6.2+ KVM and RHEV 3.0 ?
>    If they have VHBA support then pass through helps me reach the LUNs and have SCSI PR working.
>
> 3/ Also does RHEV 3.0 support direct LUN access ?
>
>   What I got to read from redhat docs is as follows.
>
> latest "BETA" release of RHEV 3.1 seems to be only having direct LUN access.
>
> http://www.redhat.com/about/news/archive/2012/8/red-hat-delivers-first-beta-for-red-hate-enterprise-virtualization-3-1

ovirt (and rhev) 3.0 have direct lun as a custom hook.
ovirt (and rhev) 3.1 have direct lun as a full blown feature

>
> New virtual machine storage features including hotplug support and direct LUN access
>
>
> SO I guess only option I have os to wait for RHEV 3.1 ?

or use the directlun custom hook with 3.0 as a temporary solution:
http://gerrit.ovirt.org/gitweb?p=vdsm.git;a=tree;f=vdsm_hooks;


>
> Again Thanks a lot for answering my queries.
>
>
> Thanks & Regards,
> -Amol
>
>
>
> -----Original Message-----
> From: Johan Kragsterman [mailto:johan.kragsterman at capvert.se]
> Sent: Thursday, August 30, 2012 12:46 PM
> To: Itamar Heim
> Cc: Sanglikar, Amol (Serviceguard); David Jaša; users at ovirt.org
> Subject: Re: [Users] [node-devel] Help required to configure shared storage on RHEL+KVM
>
> Hi!
>
> I don't think this is an oVirt discussion, but I can respond anyway, since the storage part of oVirt, imho, is a bit after in development, or has a strategy I don't really understand, perhaps. Maybe oVirt storage development strategy is hard tied to gluster?
>
> You don't tell us about the storage backend you got? If you got FC you can create an NPIV on the RHEL 6.2 host. I don't think(unsupported so far...) you can create NPIV on oVirt node or RHEL-V node, but I'm not sure about the latter...
>
>   NPIV will give you the raw LUN directly to a VHBA, but I am not sure the oVirt/KVM VM can use it the VHBA...?
>
> Or as Itamar writes, you can always use iScsi....
>
> Rgrds Johan
>
>
>
>
> -----users-bounces at ovirt.org wrote: -----
> To: users at ovirt.org, "Sanglikar, Amol \(Serviceguard\)" <amols at hp.com>
> From: Itamar Heim
> Sent by: users-bounces at ovirt.org
> Date: 2012.08.29 13:53
> Cc: David Ja&#353;a <djasa at redhat.com>
> Subject: Re: [Users] [node-devel] Help required to configure shared storage on RHEL+KVM
>
> On 08/29/2012 12:34 PM, David Ja&#353;a 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) pí&#353;e 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.
>
> _______________________________________________
> Users mailing list
> Users at ovirt.org
> http://lists.ovirt.org/mailman/listinfo/users
>