Copy mbr question

situation : 1 sata bootdisk 1 external USB disk , non boot ,just storage.
Last night i thought i use the " copy mbr " function , i was under the impression it would : copy " the mbr from my bootdisk ;like with the utility " active partition recovery " and store it as a backup file ,i was asked for a destination , so i gave my USB drive ,expecting to choose a folder next ; i didn't get it so ( thinking : the copy will be placed in the root of the drive ) i hit " commit " silly me !
So now i pasted the boot mbr onto the usb drive.
What will be the qonsequenses , i can still use the usb drive ,switch it off and on in windows.
What will happen if i reboot with the usb drive turned on ?

For safetys sake i am in the process copying the important files to another disk

Thanks,Lin

 

Lin:

Having boot code on your external USB drive shouldn't hurt anything. If you have your PC BIOS set to boot first from the internal disk then the PC won't even try to boot from the external.

If you try to boot from the external then you'll just get an error message if there are no active and bootable partitions on the external. There is no harm in leaving it as-is.

 

Thanks Mark ,i suspected this was the case ; you put my mind to rest
lin

 

If you did the "MBR Copy" running DD in Windows, DD may not have actually copied the MBR to the flashdrive so you might not have really made a change at all.

In testing, I found that DD has a problem using the "Copy MBR" function on flashdrives. If you did the procedure and looked at the flashdrive in the Disk Editor, it would show the MBR was copied. However, if you removed the flashdrive (ejecting or using Remove Safely) and reinserted it, the MBR was back at it's original state as if the copy never happened. I had to boot into the Safe Mode of DD to get the feature to work properly.

 

Paul:

I think Lin was talking about a hard disk; not a flash drive.

 

Sorry, missed that. In any case, I wouldn't trust the "Copy MBR" function without removing the device and plugging it back in and checking it with DD's Disk Editor to see if the actually got copied (assuming a copy was wanted).