On 04/30 03:44, Andrea Conti wrote: > Hi, > > > > CONFIG_PARTITION_ADVANCED=y > > > CONFIG_MSDOS_PARTITION=y > > > CONFIG_EFI_PARTITION=y > > That's all you need. > > > This could be the key. Sector sizes have been changing from 512 to 4096 > > over many years. If your kernel has been updated to expect/use 4096 byte > > sectors, it might not be able to read the disk properly. > > Sector size is only a (fixed) property of a specific block device, not > something expected or required by the kernel. > Sector sizes other than 512B have been around for ages without any problems, > even in consumer hardware (e.g. CDs and DVDs have 2KB sectors). > > > Disklabel type: dos > > > Device Boot Start End Sectors Size Id Type > > /dev/sdb1 1 1953458175 1953458175 931.5G ee GPT > > That looks... broken. > fdisk is recognizing the disk as MBR (a GPT disk would have "Disklabel type: > gpt"), but the partition table is a protective MBR, which makes no sense in a > non-GPT disk. > > My guess is that this disk was at some time partitioned with GPT (possibly it > came that way from WD?), but then it was only used in machines with no kernel > support for GPT. > Such a machine will happily treat that as a normal MBR and allow you to > access the protective entry as a normal partition, which means you can create > a filesystem on it and fill it with data, destroying the GPT structures. > > A GPT-aware kernel on the other hand will recognize that as a protective MBR > and it will ignore it --but since the disk does not contain any valid GPT > structures, it will not show any partitions. > > Try running "gdisk -l /dev/sdb"; for a valid GPT disk it will say: > > Partition table scan: > MBR: protective > BSD: not present > APM: not present > GPT: present > > If that's not the case and you have no GPT, you will have to fix things > manually. > Since the disk is only 1TB, there is no reason to use GPT at all, so your > best bet is to use fdisk to make that a standard MBR by changing the > partition type from 'ee' to '83'. > > andrea >
Hi Andreas, thank you very much for your analysis! :) when doing a gdisk -l /dev/sdb I get this Rocky Horror Picture Show: PT fdisk (gdisk) version 1.0.5 Caution: invalid main GPT header, but valid backup; regenerating main header from backup! Caution! After loading partitions, the CRC doesn't check out! Warning: Invalid CRC on main header data; loaded backup partition table. Warning! Main and backup partition tables differ! Use the 'c' and 'e' options on the recovery & transformation menu to examine the two tables. Warning! One or more CRCs don't match. You should repair the disk! Main header: ERROR Backup header: OK Main partition table: ERROR Backup partition table: ERROR Partition table scan: MBR: protective BSD: not present APM: not present GPT: damaged **************************************************************************** Caution: Found protective or hybrid MBR and corrupt GPT. Using GPT, but disk verification and recovery are STRONGLY recommended. **************************************************************************** Disk /dev/sdb: 1953458176 sectors, 931.5 GiB Model: Elements 25A2 Sector size (logical/physical): 512/512 bytes Disk identifier (GUID): BCA95A74-1E0A-4648-9971-20ED4049CAE5 Partition table holds up to 128 entries Main partition table begins at sector 2 and ends at sector 33 First usable sector is 34, last usable sector is 1953458142 Partitions will be aligned on 2048-sector boundaries Total free space is 1953458109 sectors (931.5 GiB) Number Start (sector) End (sector) Size Code Name "fix manually" scares me...especially because I have no place for 1TB of an image file to with which I can experiment ... Any ideas which could ease my burden and to un-scare my "need to fix it manually" ??? ;) ;) Cheers! Meino
