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Re: [Xen-users] Zero LVM

To: rudi@xxxxxxxxxxx, Xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Zero LVM
From: Jonathan Tripathy <jonnyt@xxxxxxxxxxx>
Date: Mon, 06 Dec 2010 16:48:52 +0000
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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



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