On Sun, Dec 04, 2016 at 09:43:41AM +0300, Constantine Kharlamov wrote: > Beforehands, the problem have been solved by removing the iso9660 > filesystem by offset. Back then the question have been asked on > forum https://bbs.archlinux.org/viewtopic.php?pid=1670463 so I still > have an output of wipefs's POV: > > $ sudo wipefs -n /dev/sdc > offset type > ---------------------------------------------------------------- > 0x1fe PMBR [partition table] GPT is always (protective) MBR + GPT header the MBR is there to keep the disk used and full for old partitioning tools that do not have a clue about GPT. MBR in this case contains one partition (type 0xee) for all disk. For example my disk: # fdisk -l /dev/sda Disk /dev/sda: 223.6 GiB, 240057409536 bytes, 468862128 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: gpt Disk identifier: E471810B-5954-48E6-B4F0-5D369ADCC514 Device Start End Sectors Size Type /dev/sda1 2048 411647 409600 200M EFI System /dev/sda2 411648 821247 409600 200M Linux filesystem /dev/sda3 821248 274087935 273266688 130.3G Linux filesystem /dev/sda4 274087936 378945535 104857600 50G Linux filesystem /dev/sda5 378945536 452476927 73531392 35.1G Linux filesystem /dev/sda6 452476928 468860927 16384000 7.8G Linux swap but if you disable GPT and enable MBR only: # fdisk --type mbr -l /dev/sda Disk /dev/sda: 223.6 GiB, 240057409536 bytes, 468862128 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x00000000 Device Boot Start End Sectors Size Id Type /dev/sda1 1 468862127 468862127 223.6G ee GPT > 0x8001 iso9660 [filesystem] > LABEL: Ubuntu 15.10 amd64 > UUID: 2015-10-21-16-17-40-00 > > I'm still curious about what happened though. α) iso9660 resides > (offset 0x8001) faar inside the real (i.e. by MBR) filesystem > (having offset 2048 ≅ 0x800). Hence, given the system shows the > label of iso9660, the system (together with most partition > utilities) assumed that sdc is using GPT. But β) I removed GPT > completely with gdisk (expert command → wipe out GPT), so unless > gdisk is buggy, it couldn't have happened! Seems like a crazy boot image that distros generate to be bootable on all possible situations. If yes, then don't waste time to try understand what the begin of the image means :-) It's almost always total mess where multiple stuff (iso, MBR, etc.) share the area. Karel -- Karel Zak <kzak@xxxxxxxxxx> http://karelzak.blogspot.com -- To unsubscribe from this list: send the line "unsubscribe util-linux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
