On Tue, Feb 19, 2008 at 12:46:28PM +0000, Daniel P. Berrange wrote: > On Tue, Feb 19, 2008 at 03:43:11AM -0500, Daniel Veillard wrote: > > > + > > > + /* > > > + * LVM requires that the first 512 bytes are blanked if using > > > + * a whole disk as a PV. So we just blank them out regardless > > > + * rather than trying to figure out if we're a disk or partition > > > + */ > > > > is it really 512 or the block size on the device used ? But 512 is > > probably sufficient for LVM to consider it cleared, just wondering ... > > The 'pvcreate' man page explicitly says the first sector > > <quote> > For whole disk devices only the partition table must be erased, > which will effectively destroy all data on that disk. This can > be done by zeroing the first sector with: > > dd if=/dev/zero of=PhysicalVolume bs=512 count=1 > </quote> > > So 512 is fine for MSDOS partition tables at least. Ahh, the legacy :-) thanks for the explanations ! Daniel -- Red Hat Virtualization group http://redhat.com/virtualization/ Daniel Veillard | virtualization library http://libvirt.org/ veillard@xxxxxxxxxx | libxml GNOME XML XSLT toolkit http://xmlsoft.org/ http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/ -- Libvir-list mailing list Libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list