Can’t open boot device

Hi Guys,
This might be a common message when you are trying to boot server after any disk replacements (boot/mirror disks) or sometimes as part of regular interval sanity reboots.

If you can see the error as "Can’t open boot device" the possible reasons would be

1. The boot disk is not powered on. (In case of external boot device (LUNS from SAN)).
2. The SCSI bus is not terminated. (can be interpreted as issues with BUS).
3. Controller level failure of some sort.
4. A disk is failing and locking the bus, preventing any disks from identifying themselves to the controller, and making the controller assume that there are no disks attached.

Solution:

• Try to boot from alternate disk and check install the bootblk on the failing disk.
• If the problem persists then check the H/W, S/W, Trans errors (Iostat -en) if count is exceeding  more than 50+ in any column its time to get that disk replaced.
• If you are unable to boot from an alternate boot disk, there is still some type of hardware problem. Similarly, if switching the failed boot disk with an alternate boot disk fails to allow the system to boot, this also indicates hardware problems.
• Being on the console switch to system controller and check the errors and contact your vendor.