clear metadata using dd?

[Eric Anderson]

On 01/23/07 12:48, Oliver Fromme wrote:
> Eric Anderson wrote:
>  > Oliver Fromme wrote:
>  > > Fernan Aguero wrote:
>  > > > adxs1, swap
>  > > > adxs2, gmirror
>  > > > adxs3, gstripe
>  > > 
>  > > Can someone please explain why such a setup makes sense?
>  > > 
>  > > As far as I can tell, the purpose of gmirror is to provide
>  > > redundancy in the case of drive failure.  I.e. if one
>  > > drive fails, the system keeps running happily instead of
>  > > crashing.
>  > > 
>  > > But if only part of the disk is mirrored, then the system
>  > > will still crash if one drive fails.  So what is the point
>  > > of using gmirror, if not on whole disks?
>  > 
>  > You might crash, but the data on the mirror on one of the disks is still 
>  > there, so you haven't lost all the data.
> 
> Right, but you have lost all the data in the partitions that
> are not mirrored.  The system is basically unusable and will
> need to be restored from backup.
> 
> In this particular case, if I understood Fernan correctly,
> the mirror contains the root file system, while all other
> data is on a gstripe (not mirrored).  So if a drive fails,
> the system crashes and all of the actual user data is
> lost.  The fact that you still have a good root file
> system on one of the disks doesn't help much in that
> situation.

Unless you don't care about the data on that partition.  For instance, a 
cvs mirror, or ftp mirror, or ISO storage area, or build directory, etc. 
  Maybe you want the mirror because you'll put home areas on it, or 
custom configs, or something else.

Anyway, the point is that you can do whatever you wish, even if it 
doesn't make sense to somebody else.. :)  Hooray for UNIX!

Eric