Re: fdisk

[Patrick Finnegan <pat@computer-refuge.org>]

On Saturday 29 May 2004 13:31, Erwan MAS wrote:
> On Sat, May 29, 2004 at 09:50:38AM -0700, Philippe Troin wrote:
> [../..]
>
> | > the first 512 byte of /dev/hda and the 512 byte of  /dev/hda1 are
> | > identical .
> |
> | That's the case if hda1 starts at cylinder 0. And it is unlike the
> | PC where the first 512 bytes (the MBR) is not part of any
> | partition.
>
> [../..]
>
> Ok in this case ,the partition table , is in the first 512 of
> /dev/hda1 .
>
> When you format /dev/hda1 , the first 512 bytes is not
>  use by any filesystem ?

Nothing except for swap partitions.  So, you should be fine as long as 
you don't start a swap partition on cylinder 0.  (Swap isn't a real 
filesystem anyways, which is why is uses the first sector of disk).

> In this context ,i have lost my partition table . After this
> command :
>  mke2fs -c -c -j /dev/hda1 .
>
> " -c -c " checks for bad blocks with writing tests .

Well, don't do that.  Just a single -c, the read test, should be enough 
to find bad blocks.  What you did is basically the same as "dd 
if=/dev/zero of=/dev/sda1" followed by a mke2fs.  If you do a normal 
mke2fs (or one -c), it won't overwrite the first disk sector (512 
bytes), which is where the disklabel lives.

Pat
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