[Sussex] Label and partition external hard drive

[Steven Dobson]

Hi Fay

On 23/02/11 18:26, 'Fay Zee' wrote:
> $ man cfdisk has a note about zeroing the first 512 bytes. When and
> why does this apply?
> 
> When I first ran # cfdisk /dev/sdf on the new disk I saved the
> intitial printout:
> (I don't know what the asterisks signify.)
> 
>     Name          Flags        Part Type    FS
> Type            [Label]           Size (MB)
>  -------------------------------------------------------------------------------------------
>                                
> Pri/Log     Free
> Space                               
> 1.05  *
>     sdf1                       
> Primary     NTFS              
> [^R]              159996.97  *
>                                
> Pri/Log     Free
> Space                               
> 0.13  *
> 
> which showed there was 1.05MB of free space before the first
> partition, which happens to be marked as NTFS.

An asterisk after the partition size shows that the partition is not
aligned on a cylinder boundary.  That is not optimal for most *nix file
systems I believe as most try and group blocks from a file onto the same
track and cylinders for speed on reading - no head movements required!

> I didn't notice that when I deleted the partitions, so I just created
> my first partition right at the beginning, gave it the label "XP" and
> then ran # mkntfs -L "XP" "/dev/sdf1" to build the NTFS file system.
> It took exactly 25 minutes.

It will take as long as it takes.  XFS is very much quicker at
formatting as it doesn't need to write as much data to a new partition.
 That is one of the reasons I use it.  Took a little while on my 1 & 1.5
TB drives - but much quicker than ext2/3 would have.

<snip disk layout>

> The other difference is that the first printout showed that none of
> the partitions were set as bootable, whereas when I tried to write my
> new partitions to the disk a message told me I needed to set one as
> bootable.

I think the message is more along the lines that with out a bootable
partition then a computer can't boot from it.  This is true, and
probably undesirable if you were partitioning a disk for the OS to be
installed on.  But for an external, removable disk which you're never
going to boot off it's not a problem at all.

In fact if you make one of the USB disk partitions bootable and try and
reboot with the USB disk still plug in then it's bootablility (is that a
word?) might take precedence and stop your computer from booting.

I believe it is save to go back in to cfdisk and remove the boot flag
from a configured filesystem partition.

-- 
Steve "Dobbo" Dobson