Friday, May 4, 2012

Supermicro USB Boot Issues, H8SGL

Thought I'd pass on a small tidbit;

A SuperMicro H8SGL(-F) won't boot from USB properly when there are more than 12 bootable items in the server.

In my case, filling my enclosure with drives surpassed this limit.  Quite the surprise, as it was working great with 8 drives in, but at 16 drives, a routine maintenance reboot left it unable to start again.

The symptom is : It will just act like there isn't a boot sector on the USB drive.

I'm unsure at this stage if it's just USB, or if it's any bootable device.

I'm guessing that the MB's BIOS keeps a very short table of bootable items, and as it discovers more, the first to be discovered scroll off and are no longer available, even when they still list on a F11 Boot Selection.

I fixed it by turning off the BIOS boot option inside my SAS adapter's BIOS, and everything was fine.

It goes to show that you _ALWAYS_ need to reboot a server after any hardware/software changes, just to make sure. If I had learned about this problem when we were in some sort of urgent situation where I needed to quickly power cycle this server, well, that would have been a bad thing.



  1. w00t!
    Thanks for this! We were bashing out heads against this for longer than I'd like to admit. We have 10 other SM that we did not have this issue with. But one did.
    Saved out bacon!

  2. Thank you! I had the same problem and wasted hours and hours over the last day trying to figure it out. I added 14 new disks to my 24 bay supermicro chassis and suddenly it stopped booting from the USB drive that had worked for many months. Updating the bios did nothing, only disabling the bios boot option on the HBA solved the problem the "right way".