Le 22/07/2017 à 14:52, Felix Miata a écrit :
Pascal Hambourg composed on 2017-07-22 11:03 (UTC+0200):Felix Miata composed:at least one primary is always EXT2 with Grub Legacy and little else, unless the disk is a pure data-only disk, in which case its MBR sector is empty but for the partition table.If this disk is bootable by BIOS, then its MBR must contain a boot program, at least the DOS/Windows standard MBR program or compatible (such as the ones installed by install-mbr or lilo -M).By definition, a data-only disk is not bootable.
Yes, I missed the "unless the disk is a pure data-only disk" part. Sorry for the noise.
On my data-only disks I use a sector editor if necessary to fill the first 446 bytes of its first sector with nulls.
A "modern" MBR contains an optional 32-bit disk signature at offset 440. Fdisk calls it "disk identifier" and recent enough kernels uses it to create synthetic partition UUIDs (PARTUUID) for the partitions. Wiping the first 446 bytes erases this signature.