Sunday, January 17, 2016

USB drive - standard sector size

I've been spending some time trying to find why "NTLDR is missing" sometimes happens on Windows Vista/7/8/10, and I was reading an article about unbootable Windows 7 systems, and it mentioned that the BIOS loads the MBR into RAM, then executes the MBR code, the MBR code then loads the first sector of the active partition (called the WBR) into RAM, then executes the  WBR code. This code is NTLDR for NT/2000/XP and bootmgr for Vista/7/8/10.

So I figured I would make a Windows PE disc and play around inside my Windows 10 laptop, and while trying to use a 2 gig flash drive with Rufus, I got this error:

Nonstandard sector size detected
Conventional drives use a 512-byte sector size but this drive uses a 2048-byte one. In many cases, this means you will NOT be able to boot from this drive.
Rufus can try to create a bootable drive, but there is NO WARRANTY that it will work.

This might be especially important to me, because I always wondered why some USB drives would work for my NTLDR boot disk, and why some wouldn't. Perhaps this sector size issue is related.

I'll try to test more, and perhaps if Rufus is a better way to make the USB stick, use it instead.

Until then, if you have been having a problem with making the bootable drive, and you are using a 2gig or smaller USB, try larger than 2gigs, or the opposite; if larger wasn't working, try smaller.

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