CentOS - Dec 2016 - Strange (?) device.map in CentOS 7 VM installations

Hello,

After repeated failing efforts to restore CentOS 7 backups (taken using 
mondorescue software), I have found that all my CentOS 7 installations 
(VMs under KVM) have the same /boot/grub2/device.map, which seemingly 
refers to two HDs, although the VMs in fact include only one (virtual) HD.

For example: /boot/grub2/device.map

    # this device map was generated by anaconda
    (hd0)      /dev/vda
    (hd1)      /dev/vda

Here is the hardware of the VM:

    # parted -l
    Model: Linux device-mapper (linear) (dm)
    Disk /dev/mapper/centos-swap: 2147MB
    Sector size (logical/physical): 512B/512B
    Partition Table: loop
    Disk Flags:

    Number  Start  End     Size    File system     Flags
      1      0.00B  2147MB  2147MB  linux-swap(v1)

    Model: Linux device-mapper (linear) (dm)
    Disk /dev/mapper/centos-root: 18.8GB
    Sector size (logical/physical): 512B/512B
    Partition Table: loop
    Disk Flags:

    Number  Start  End     Size    File system  Flags
      1      0.00B  18.8GB  18.8GB  xfs

    Model: Virtio Block Device (virtblk)
    Disk /dev/vda: 21.5GB
    Sector size (logical/physical): 512B/512B
    Partition Table: msdos
    Disk Flags:

    Number  Start   End     Size    Type     File system  Flags
      1      1049kB  525MB   524MB   primary  xfs          boot
      2      525MB   21.5GB  20.9GB  primary               lvm

This is NOT the case with my CentOS 5 and CentOS 6 VMs, which all have a 
"correct" device map, with a single (hda0) entry.

Is the above behavior expected? If not, what should be the expected way 
of operation and what may be the cause of it?

I am trying to understand where something may be going wrong, so please 
help.

Many Thanks!
Nick

On 29/12/2016 11:24 ??, Nikolaos Milas wrote:
> ...I have found that all my CentOS 7 installations (VMs under KVM) 
> have the same /boot/grub2/device.map, which seemingly refers to two 
> HDs, although the VMs in fact include only one (virtual) HD.
> ...
> This is NOT the case with my CentOS 5 and CentOS 6 VMs, which all have 
> a "correct" device map, with a single (hda0) entry.
>
> Is the above behavior expected? If not, what should be the expected 
> way of operation and what may be the cause of it?
>
> I am trying to understand where something may be going wrong, so 
> please help.
>
Hello,

I never got a reply on this, so I repeat the question:

Is it normal in CentOS 7 to have a device map with two entries esp. when 
the (physical or virtual) hardware  has only one hd ?

Is the following normal?

     /boot/grub2/device.map:

        # this device map was generated by anaconda
        (hd0)      /dev/vda
        (hd1)      /dev/vda

Please advise!

Thanks,
Nick

On 01/04/2017 03:07 AM, Nikolaos Milas wrote:
> Is it normal in CentOS 7 to have a device map with two entries esp. 
> when the (physical or virtual) hardware  has only one hd ? 

I don't see that on VMs that I manage.  Some of the physical machines 
that I manage do have duplicates in the device.map.