Hai

I have fedora core4 on my samsung HDD which is hdb( primary slave). When i changed my samsung HDD to hda (primary master) GRUB loader is not able to boot linux. whats the problem

Do you have another drive on the system your swapping it with? I'm guessing the problem is that grub no longer knows were to find the Stage2 files.

Grub keeps a device map to identify the drives. It is the /boot/grub/device.map

You cannot do the thing you have described in Linux because unlike Windows every partition is unique in Linux.

Your boot loader is with the primary partition so swapping it you have no access to the MBR. If the slave isn't bootable then the BIOS will summon the master to boot. However due to your swapping BIOS has to call your master as hdb and gave hda title to the slave. Got it?

Hai

Let me explain briefly. I have a samsung and a segate HDD. Segate is primary master and samsung is primary slave. I use samsung for testing purposes. so i removed my segate hdd which is primary maser. Then i installed fedora core on samsung hdd which is primary slave and i installed GRUB on samsung MBR (for this reason i removed segate which is primary master). Then i connected both the drives, if i wanted to boot linux i will press f8 and the choose samsung hdd(primary slave). the problem is that when i change the jumper settings of samsung hdd to make it primary master GRUB is not able to boot linux. whats the problem

If you havdSeagate as the master and jumpered the the slave Samsung as another master your BIOS will be confused.

Unlike Windows any partition can be C, D, E and so on and their positions are determined purely by the order in the booting queue, Linux's partitions are uniquely named. The 4 primary partitions are always 1 to 4 and logical starts at the 5th partition regardless if any of them is created or not.

In a similar maner the first IDE is called hda, 2nd hdb, 3th hdc all according to the IDE channel you plug the disks.

Therefore when installed alone your Linux has address stamped inside that it was in hda, as you did remove the Seagate.

Putting your Seagate back into the box your Samsung will be detected as hdb if it boots at all. If Linux's boot loader were given access to the PC all it can do is to boot the hda1 on which it was created. So swapping disk in Linux is not as simple as in Windows. OK?

Now the cure-------------------

You can maintain your Samsung as the master, Seagate as the slave and dual boot the two.

The standard boot loader for FC4 is Grub. A text file is used to control its booting and it is always the /boot/grub/menu.lst. When you hook up the two as suggested, you can only boot FC4, right. That is OK, just log in as root (need root's privilege to amend system files).

In the desktop go to open /boot/grub/menu.lst with gedit or kwrite and add these 3 lines to the end

title the dude said this is my first dual boot to Windows/Linux
root (hd1,0)
chainloader +1

save the file. On re-boot whatever you got in the slave first partition will be booted by Grub, if it was bootable on its own before. This will work regardless if it is a Dos, Win3x, Win9x, 2k/XP, any Linux, any BSD or even Solaris.

Grub counts from 0 therefore (hd0,0)=hda1, (hd1,0)=hdb1 and so on.

The arrangement you have is what I described to dual boot Linux and WIndows but keeping Windows's MBR untouched as a virgin.