P2V fun?

We have a good number of servers which are being moved from physical to virtual.  In our case VirtualBox is the virtualization solution.  If you have not heard of VirtualBox, as a result of the Sun acquisition, it is an Oracle product.

In my opinion VirtualBox has certainly not suffered since Oracle rebranded it.  It is still available free of charge and is updated on a regular basis.  In addition to overall stability, running on Windows, Linux, and OS X hosts is an attractive, and in our shop, needed feature.

Moving physical CentOS servers to VirtualBox proved to be a bit of a challenge.  There are a lot of good blog posts and HOWTOs on this subject.  If minimal downtime is a must, this and other rsync-based solutions is worth reading.

As it turns out regardless of the solution I used, ultimately I could not boot the resulting virtual server without using a "linux rescue" or "live distro" and then chroot'ing or mounting the converted filesystems.  On the one hand this was a comfort because I was able to confirm the conversion of the physical disks to a VDI, VDMK, etc.  On the other hand I had a few servers to go and not making headway on such an otherwise simple procedure is not a happy place.

Variations of the "/dev/root not found" error became all too familiar.  Updating GRUB, mkinitrd, vgscan, etc. are among the tried but no luck solutions I was able to find.  Several posts suggest a bad or "too new" version of the CentOS kernel.  I also went down the logical volume manager rabbit hole after reading a good number of posts.

Given that I created my virtual disks using three different methods and could confirm the existence and readability of my files, I figured it had to be hardware-related or at least virtualized hardware.  Ultimately it turned out to be controller card.  Moving the drive from an SATA to a SCSI controller (as one suggested) did not work.  However, moving to the IDE controller where the CD/DVD drive was attached by default proved to be the winning combination.

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