On 06.02.2014 12:05, C. L. Martinez wrote: > On Thu, Feb 6, 2014 at 11:01 AM, Dennis Jacobfeuerborn > <dennisml@xxxxxxxxxxxx> wrote: >> On 06.02.2014 11:45, C. L. Martinez wrote: >>> Hi all, >>> >>> I have a strange problem when I use lvm disks to expose to virtual >>> guests (host is CentOS 6.5 x86_64). If I remove a kvm guest and all >>> lvm disks attached to it, and I create a new kvm with another lvm >>> disks that use the same disk space previously assigned to the previous >>> kvm guest, this new guest sees all partitions and data. Creating new >>> lvm volumes with different names to this new kvm doesn't resolves the >>> problem. >>> >>> Any idea why?? >> >> When you delete a volume the data isn't cleared only the metadata >> removed so if you later create a new volume that ends up using the same >> area on disk then you will see the old data as expected. >> If you don't want this to happen then you need to overwrite the volume >> before you delete it. >> >> This is a general issue in virtualization/clouds that you need to take >> into account for security reasons. See for example: >> https://github.com/fog/fog/issues/2525 >> >> Regards, >> Dennis > > > Many thanks Dennis ... Then if I do: > > dd if=/dev/zero of=/dev/sdc1 bs=1M (it is a 1TiB disk), will erase all > data and partitions created by the kvm guest?? That should work although if you want to be really safe you should probably use /dev/urandom instead of /dev/zero as using random data is a better way to deal with the problem of data remanence: http://en.wikipedia.org/wiki/Data_remanence#Overwriting Regards, Dennis _______________________________________________ CentOS-virt mailing list CentOS-virt@xxxxxxxxxx http://lists.centos.org/mailman/listinfo/centos-virt
