[CentOS] Question re: CentOS-6.0, KVM, and /dev/sr0

I am experimenting with KVM and I wish to create a virtual machine
image in a logical volume.  I can create the new lv without problem
but when I go to format its file system then I get these warnings:

Warning: WARNING: the kernel failed to re-read the partition table
on /dev/sda (Device or resource busy).  As a result, it may not
reflect all of your changes until after reboot.
Warning: Unable to open /dev/sr0 read-write (Read-only file system).
 /dev/sr0 has been opened read-only.

When I take a look at things using parted I see this:

# parted -l print
Model: ATA WDC WD5000AAKS-0 (scsi)
Disk /dev/sda: 500GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End    Size   Type     File system  Flags
 1      1049kB  525MB  524MB  primary  ext4         boot
 2      525MB   500GB  500GB  primary               lvm


Model: Linux device-mapper (linear) (dm)
Disk /dev/mapper/vg_inet02-lv_guest01: 129GB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number  Start  End    Size   File system  Flags
 1      0.00B  129GB  129GB  ext4


Model: Linux device-mapper (linear) (dm)
Disk /dev/mapper/vg_inet02-lv_log: 1049MB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number  Start  End     Size    File system  Flags
 1      0.00B  1049MB  1049MB  ext4


Model: Linux device-mapper (linear) (dm)
Disk /dev/mapper/vg_inet02-lv_tmp: 8389MB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number  Start  End     Size    File system  Flags
 1      0.00B  8389MB  8389MB  ext4


Model: Linux device-mapper (linear) (dm)
Disk /dev/mapper/vg_inet02-lv_home: 4194MB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number  Start  End     Size    File system  Flags
 1      0.00B  4194MB  4194MB  ext4


Model: Linux device-mapper (linear) (dm)
Disk /dev/mapper/vg_inet02-lv_swap: 8321MB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number  Start  End     Size    File system     Flags
 1      0.00B  8321MB  8321MB  linux-swap(v1)


Model: Linux device-mapper (linear) (dm)
Disk /dev/mapper/vg_inet02-lv_root: 53.7GB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number  Start  End     Size    File system  Flags
 1      0.00B  53.7GB  53.7GB  ext4


Warning: Unable to open /dev/sr0 read-write (Read-only file system).
 /dev/sr0
has been opened read-only.
Error: /dev/sr0: unrecognised disk label

The host system is CentOS-6.0 with updates applied.  I did a manual
disc configuration on initial install but I do not recall
specifically dealing with /dev/sr0 at any point.

Can anyone explain to me what is happening here and what I should
do?  Am I constrained to reboot the server each time that I make
changes to an LV?  Is there some configuration change I need make to
the base system?

The favour of a direct copy of any reply to the mailing list is
requested as I am a digest subscriber.

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James B. Byrne                mailto:ByrneJB at Harte-Lyne.ca
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