Long ago, in a galaxy far far away, I managed to hookup an 80GB IDE to a very old machine containing a 4-drive SCSI bay in a RAID5 for a total of 24GB usable diskspace.
With sweat pouring down my brows and a sigh of relief that the 80GB IDE HDD was detected, my next greatest challenge was to boot from a CD. Fortunately, I managed to boot from Ultimate Boot CD and used a tool to do a sector-by-sector clone of this server.
Months later, this server died hard with no spare parts available due to its age, lack of value, and lack of financial resources. 8-12 months later, one of the employees is requesting access to a piece of a software called SugarCRM that was on this server as they need to extract data despite being told to do it ahead of time.
Luckily (or not) I have this 80GB IDE HDD with a clone of the server's logical drive. So I make a sector-by-sector backup image using Acronis, and then I try to boot a virtual machine using this physical drive as its primary and only harddrive storage device. I get the following errors:
VFS: Cannot open root device "3003" or 30:03
Please append a correct "root=" boot option
Kernel panic: VFS: Unable to mount root fs on 30:03
I also made sure that I used something compatible like 1 physical CPU with 1 vCore, 1GB of RAM (could have done something overkill, but considering the kernel and OS could be old enough, it would be wisest to use small compatible numbers).