How to create sda partition on VM

Latest response

Hi,
Is there any way to create sda partitions instead of vda on new VM.

Please let us know the steps!!!

Thanks

NM
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Responses

Russell Goldberg's picture Active Contributor 392 points
21 August 2017 10:00 PM

Changing the virtual disk's interface type from fully-virtualized (virtio-blk) to para-virtualized (virtio-scsi) should result in the OS seeing the disk as /dev/sda instead of /dev/vda.

NM Active Contributor 165 points
22 August 2017 12:03 PM

Hi, Thanks for your quick reply.

My Observations: 
  -> I created disk with option "VirtIO-SCSI" on my new VM-1 and installed RHEL as host OS. Here I observed that partitions are created with sda.

I am attaching screenshot of RHEL partition details.

  -> I created disk with option "VirtIO-SCSI" on new VM-2 and installed WindRiver as my host OS. Here I observed that it is showing vda.

I am attaching screenshot of WRL.

My requirement is I need "sda" partitions for my new VM. Can you suggest which option I should opt when I am creating VM. OR how to achieve this?

Steven Yuen Fay Tsang's picture Active Contributor 220 points
22 August 2017 12:13 PM

Hi Nani Babu Mutte,

why do you explicity need sda?

Full Virtualization vs. Paravirtualization

/dev/sda is the first detected disk of IDE/SATA/SCSI type. In this case, emulated(full virtualized) by the hypervisor.

/dev/vda is the first detected paravirtualizated disk driver. It is faster than emulated sdX devices.

Christian Labisch's picture Guru 9710 points
22 August 2017 12:17 PM

Hi Nani,

I don't quite get the point ... when you insert the virtual disk into a SATA controller, it is shown as sda and when you insert the virtual disk into a VirtIO controller, it is shown as vda ... so when you want to see sda - just insert the virtual disk into the SATA controller. :)

Regards,
Christian

NM Active Contributor 165 points
22 August 2017 6:11 PM

Hi Guys, I need clarity on partitions created differently on 2 VM's even though I opted same ''VirtIO-SCSI" option while creating disk.

Please check above screenshots

  -> I created disk with option "VirtIO-SCSI" on my VM-1 and installed RHEL as a host OS. Here I observed that partitions are  automatically created with sda.
  -> I created disk with same option "VirtIO-SCSI" on my VM-2 and installed WindRiver as my host OS. Here I observed that it is showing vda.

Thanks in Advance!!!

Russell Goldberg's picture Active Contributor 392 points
22 August 2017 6:32 PM

My guess is that the "WindRiver" OS does not have the virtio-scsi drivers necessary to make use of the para-virtualized disk device you're attempting to present to it.

As a result, the disk is being represented as fully-virtualized (/dev/vda) disk by the OS despite your selecting virtio-scsi as the interface type.

To test this, you can attempt to locate the virtio-scsi drivers on your WindRiver VM (note that these drivers are installed by default in RHEL):

locate virtio_scsi.ko

If you're unable to locate the virtio-scsi driver, then your system will probably not be able to make use of the virtio-scsi interface type, and your disk devices will likely always be represented as /dev/vda, vdb, vdc, etc.

Christian Labisch's picture Guru 9710 points
23 August 2017 6:57 AM

Hi Nani,

One thing, you say that you installed RHEL in VM-1 and Wind River in VM-2 as host. I guess you mean you installed these systems as guest systems on a RHEL host system. So it is possible that the explanation from Russell is valid and in that case there's nothing you can do, you have to live with the situation as it is. But is this a problem at all ? Important is that the virtual systems are running properly - right ?

Regards,
Christian

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