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Thread: Grub Error 21
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- Join Date
- Jan 2007
My problem isn't to do with booting. It is more of the reliability of reading an external USB disk.
I am typing this post using the Mandriva installed into the external USB with PC3. For some reason it suddenly decided to recognise the USB disk after I inserted an internal hard disk into the PC.
Grub now confirms my USB hard disk is (hd1) and so the installation when it was (hd0) without any disk would not work. However as in a Grub prompt I cam amend the (hd0) reference to (hd1) so I have booted Puppy, then Slax and now Mandriva, using a Grub floppy.
I would have to try PC1 and PC2 later. If the PC recognises the USB hard disk then there is no problem in booting it.
There is something odd about my (hd1) too. When I want to see the partitions by terminal commandCode:
unable to seek /dev/sda
It is getting better everytime.
I confirmed all my 4 Linux in the external USB hard disk had the "unable to seek" error in fdisk. cfdisk wouldn't load at all.
However when I removed the USB hard disk and insert it back as an internal disk in the PC, fired up a Live CD I could see the disk with cfdisk and fdisk program working again.
I then return the disk back to the external enclosure and boot again as an external USB device the problem disappears completely as nothing had happened.
My external USB hard disk (without any internal hard disk) now boots perfectly to any one of the 4 installed distros in my PC3 computer.
The acid test will come later when I try to move it to PC1 and PC2.
- Join Date
- Jan 2007
OK guys, I got good news.
After I managed to get only one of the three PC to boot 4 distros of Puppy, SLax, Mandriva and Sidux I tried the USB external disk on two more PCs.
PC4 : Asus A8V-E with a AMD64 3200
PC5 : Advant laptop with a Pentium
I didn't ask PC4 and PC5 to boot to the USB disk, but just boot to a Grub floppy and check if Grub could see the USB disk. To my surprise both did. Thus even without changing the Bios I could boot up "manually" the 4 distros in the USB with varying degree of success. Remember the 4 distros were installed for PC3 and the installed hardware drivers cannot apply directly to every other PC. Nevertheless I was convinced the external USB hard disk works on 3 out of the 5 PCs.
At this point I went back to PC2 and try to install Puppy on a pen Drive there. It didn't work first so I investigated the BIOS setting and discovered the culprit that has been stopping me from booting the USB device----> My USB legacy support in both PC1 and PC2 were disabled. I can't remember when I last disabled it but in oder to boot from a USB device one of the necessary step is to enable the USB legacy support.
After I enabled the USB legacy support the two remaining PCs boot up the external USB hard disk too.
I have Slax installed in one of the 4 distros. Slax uses ram for its root and so the partition reference is unimportant. It boots successfully in all 5 PC from the USB hard disk and that is the proof I need to show it works.
Therefore I have to withdraw my assertion that Grub cannot recognise a USB device because it can if the USB legacy support is switched on. Sorry for my mistake but I hope at least you get the solution you want.
If you still have any problem in the installation or booting just post the problem here. I am reasonably certain that I have the problem licked. There is always some teething troubles in booting from a USB hard disk like kernel panic because of not syncing but in the main there should be sufficient distros that can run satisfactorily in the USB hard disks.
I now put down the previous difficulty of PC1 not able to recognise the USB hard disk to a bad connection as I found out the USB key wasn't always pushed fully home.