fdisk /mbr

[Demosthenes]

What does it do precisely? And how dangerous is it?

The reason I ask is that I have a geometry error on one of my disks. Apparently some partition is reported to start on head 2, though I think I only have 2 heads on the drive (otherwise I do not think it would give me an error). It dual boots with some Linuxes, MS Win98, and MS Win2k. All partitions boot fine, so nothing is bothering me, but if rebuilding the partitions is relatively safe, might as well do it.

I take that after rebuilding it would boot to the first partition (Win98) and I would have to reinstall the boot loaders?

Respectfully,

Demosthenes

[lpc300]

Hi Demosthenes,

I'm assuming that you use either Lilo or Grub and, if you are not chosing Linux, you go to the Win2K boot loader (with Win2K and Win98). Running fdisk/mbr will clear the master boot record, deleting either Lilo or Grub (or Boot Magic or System Commander, if you use them), but will leave the Win2K boot loader (with Win2K and Win98) intact.

In order to access your Linux partition, you will need to reinstall whatever you used to access it.

Hope this helps.

[Demosthenes]

I currently run emulation software for my MS Windows desktop, so I was thinking of wiping all my Linux partitions off and making one machine a dedicated Microsoft machine. I am good with reinstalling boot loaders and such, but I really wanted a description of how fdisk /mbr works. Since the Microsoft boot loader remains, I assume it is put on the primary partition (Win9x in my case).

But, I still have to ask, will fdisk /mbr solve the geometry error? And, will it have any adverse effect, like lost data?

Respectfully,

Demosthenes

[glc]

If you put fdisk /mbr into a Google search, you will come up with some quite technical articles which will hopefully give you the info you are seeking. The one that links to claws-and-paws.com might be what you are looking for.

[Demosthenes]

Thanks glc, I did a net search after the posting and read my Mueller bible, but the claws-and-paws site had some nice information. Always wondered how mbr infecting programs worked. But, looks like fdisk only rewrites the executable code, not the partition table information.

Anyway, I got my Partition magic out, and it seems the extended partition on a 40 gig drive crosses the 1024 cylinder boundary and is not marked as an ExtendedX partition. PQMagic will fix it, but I am still hesitant to do it. Guess I will have to look this one up, but in the mean time, any suggestions?

Respectfully,

Demosthenes

[glc]

No suggestions from this end except maybe see if Powerquest can shed some light on it?

[Demosthenes]

Well, I decided to go through with it. Ten CD-Rs and 6 hours later (I am running a 4x mind you), I had most of my information backed up.

Tt was an easy enough hex edit to change the type of the partition to an ExtendedX, but this did nothing to solve the geometry problem on the last partition. Anyway, partition magic would not load with the error, so I resorted to the partitioning prog on the mandrake install. It killed everything and I was left with just my MS Windows. Unfortunately, I should have fdisked the mbr first, since the Linux loader did not load. A quick boot disk solved this, and I am back on track.

First, the Microsoft boot manager is still residing on the primary active partition (the only one left now). So, is the bootloader contained entirely in the \boot.ini file? Second, I am thinking of putting XP on the machine, so can anyone tell me the footprint of a full install?

Respectfully,

Demosthenes