Re: [Xen-users] Zero LVM

[Jonathan Tripathy <jonnyt@xxxxxxxxxxx>]

On 06/12/10 16:45, Rudi Ahlers wrote:
> On Mon, Dec 6, 2010 at 6:24 PM, Jonathan Tripathy<jonnyt@xxxxxxxxxxx>  wrote:
> > Hi Everyone,
> >
> > When providing Xen guests to cutomers, it is important to make sure that the
> > LVM LV is "zeroed" before use. What is the correct syntax to do this?
> What do you mean it should be "zero'd" ?
Most regular file systems do not actually remove files from disk when 
using standard commands such as rm or del. They block are simply marked 
as "ignore". This means that if you delete an LV, then create a new one, 
you run the risk of using the same physical portions of the physical 
disk...which still contains data (marked as "ignore). This means that 
your new customer could just simple do a disk dump and view all of this 
data.
By zero'ing, you write 00000.... to the whole LV before placing your OS 
on top, so no data from past customers is available
Hope this helps

Cheers

Jonathan

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