3TB disc and block alignment

perryh at pluto.rain.com perryh at pluto.rain.com
Wed Feb 23 09:11:18 UTC 2011


Pete French <petefrench at ingresso.co.uk> wrote:

> > Why may it hurt ? How may it hurt ? Which sector is written to
> > by this 'gpart' command ?
> >
> > As far as I understand, GPT writes some stuff at the beginning
> > and the end of the harddisk.
>
> Yup, this is true.
>
> > How/why will the newfs overwrite those parts ?
>
> Because you are also giving it the whole hard disc to write to,
> instead of a partition within the hard disc, so you will end up
> scribbling on what you wrote with the gpart command.

Certainly the _correct_ thing to do is to create a partition, and
newfs that.  However, it's not entirely clear why the OP is not
getting by with this mistake, because newfs (for a UFS filesystem)
doesn't write anything ahead of the superblock -- unless asked to
install bootblocks.


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