Hi, I zero-filled first 10MiB of my SSD(dd if=/dev/zero of=/dev/sda bs=10M count=1). As expected, this wiped my primary GPD header and first partition. Before the wipe, GPT was following: Disk /dev/sda: 250069680 sectors, 119.2 GiB Logical sector size: 512 bytes Disk identifier (GUID): 2EFD285D-F8E6-4262-B380-232E866AF15C Partition table holds up to 128 entries First usable sector is 34, last usable sector is 250069646 Partitions will be aligned on 1-sector boundaries Total free space is 16 sectors (8.0 KiB) Number Start (sector) End (sector) Size Code Name 1 34 58593784 27.9 GiB EF00 root part 2 58593785 234375035 83.8 GiB 0700 home part 3 234375036 250069630 7.5 GiB 8200 swap part However, to my surprise, the file(1) and dumpe2fs(8) utilities were still able to show information regarding file system: root@T60:~# file -s /dev/sda1 /dev/sda1: sticky Linux rev 1.0 ext4 filesystem data, UUID=88e70e1b-4c45-4e7e-931f-9e97d7257ee8 (needs journal recovery) (extents) (large files) (huge files) root@T60:~# dumpe2fs /dev/sda1 dumpe2fs 1.42.5 (29-Jul-2012) Filesystem volume name: <none> Last mounted on: / Filesystem UUID: 88e70e1b-4c45-4e7e-931f-9e97d7257ee8 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize Filesystem flags: signed_directory_hash Default mount options: (none) Filesystem state: clean Errors behavior: Continue Filesystem OS type: Linux Inode count: 1831424 Block count: 7324218 Reserved block count: 366210 Free blocks: 4511822 Free inodes: 1671701 First block: 0 Block size: 4096 Fragment size: 4096 Reserved GDT blocks: 1022 Blocks per group: 32768 Fragments per group: 32768 Inodes per group: 8176 Inode blocks per group: 511 Flex block group size: 16 Filesystem created: Wed Jul 10 23:01:50 2013 Last mount time: Mon May 5 19:28:01 2014 Last write time: Mon May 5 19:28:01 2014 Mount count: 14 Maximum mount count: 34 Last checked: Sun Jan 26 15:32:00 2014 Check interval: 15552000 (6 months) Next check after: Fri Jul 25 15:32:00 2014 Lifetime writes: 61 GB Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 256 Required extra isize: 28 Desired extra isize: 28 Journal inode: 8 First orphan inode: 1439005 Default directory hash: half_md4 Directory Hash Seed: f7476ad6-3067-4697-93b3-f4a368d76eab Journal backup: inode blocks Journal superblock magic number invalid! root@T60:~# Am I correct that there are multiple super-blocks scattered around the HDD and if first one is missing, then next one is read by file or dumpe2fs utilities? In the first place, what (important) file-system data is written at the beginning of the partition? regards, Martin _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
