1. Start the VM, and attempt to log in through the VNC. The following message is displayed: Boot failed: not a bootable disk.
The possible causes are as follows:
a. The image is damaged.
b. The image data is incorrect, and cannot guide through OS boot based on the disk information.
2. Use the hexdump tool to check the 1024 bytes of the VM image file header. It is found that the first 512 bytes are tar command-related information, as shown in Figure 1. (0x00000200 = 512 bytes).
Figure 1 First 512 bytes
The later 512 bytes are the OS boot data, as shown in Figure 2.
Figure 2 OS boot data
3. The user mistakenly used the tar command to compress the image file, causing incorrect image file header data. For a .raw VM image, the first 512 bytes must be OS boot information so that the OS can start properly.