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标题：ext3/ext4 超级块修复

作者：惜分飞©版权所有[未经本人同意,不得以任何形式转载,否则有进一步追究法律责任的权利.]

创建ext4文件系统

[root@localhost ~]# mkfs.ext4 /dev/sdb1
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1310720 inodes, 5242624 blocks
262131 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2153775104
160 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000

Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

[root@localhost ~]# mkdir /sdb
[root@localhost ~]# mount /dev/sdb1 /sdb
[root@localhost ~]# df -h
Filesystem           Size  Used Avail Use% Mounted on
/dev/mapper/ol-root   36G  4.0G   32G  12% /
devtmpfs             1.8G     0  1.8G   0% /dev
tmpfs                1.8G     0  1.8G   0% /dev/shm
tmpfs                1.8G  8.9M  1.8G   1% /run
tmpfs                1.8G     0  1.8G   0% /sys/fs/cgroup
/dev/sda1            497M  195M  303M  40% /boot
tmpfs                369M     0  369M   0% /run/user/0
/dev/sdb1             20G   45M   19G   1% /sdb

准备测试数据

[root@localhost sdb]# cd /etc/sysctl.d/
[root@localhost sysctl.d]# ls
99-sysctl.conf
[root@localhost sysctl.d]# cp 99-sysctl.conf /sdb
[root@localhost sysctl.d]# more 99-sysctl.conf
# System default settings live in /usr/lib/sysctl.d/00-system.conf.
# To override those settings, enter new settings here, or in an /etc/sysctl.d/<name>.conf file
#
# For more information, see sysctl.conf(5) and sysctl.d(5).

破坏ext4文件系统

[root@localhost ~]#  dd if=/dev/zero of=/dev/sdb1 bs=1024 count=5
5+0 records in
5+0 records out
5120 bytes (5.1 kB) copied, 0.00270838 s, 1.9 MB/s
[root@localhost ~]# mount /dev/sdb1 /sdb
mount: unknown filesystem type '(null)'

日志报错

[ 8868.362628] sd 32:0:1:0: [sdb] Cache data unavailable
[ 8868.362632] sd 32:0:1:0: [sdb] Assuming drive cache: write through
[ 8868.363714]  sdb: sdb1
[ 8868.390297] sd 32:0:1:0: [sdb] Cache data unavailable
[ 8868.390301] sd 32:0:1:0: [sdb] Assuming drive cache: write through
[ 8868.391462]  sdb: sdb1
[ 8900.130143] EXT4-fs (sdb1): mounted filesystem with ordered data mode. Opts: (null)
[ 8900.130163] SELinux: initialized (dev sdb1, type ext4), uses xattr
[ 8902.803966] sdb1: WRITE SAME failed. Manually zeroing.

fsck修复

[root@localhost ~]# fsck -t ext4 /dev/sdb1
fsck from util-linux 2.23.2
e2fsck 1.42.9 (28-Dec-2013)
ext2fs_open2: Bad magic number in super-block
fsck.ext4: Superblock invalid, trying backup blocks...
/dev/sdb1 was not cleanly unmounted, check forced.
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Free blocks count wrong for group #1 (31740, counted=31739).
Fix<y>? yes
Free blocks count wrong (5116302, counted=5116301).
Fix<y>? yes
Free inodes count wrong for group #0 (8181, counted=8180).
Fix<y>? yes
Free inodes count wrong (1310709, counted=1310708).
Fix<y>? yes

/dev/sdb1: ***** FILE SYSTEM WAS MODIFIED *****
/dev/sdb1: 12/1310720 files (0.0% non-contiguous), 126323/5242624 blocks

测试修复结果

[root@localhost ~]#
[root@localhost ~]#
[root@localhost ~]# mount /dev/sdb1 /sdb
[root@localhost ~]# df -h
Filesystem           Size  Used Avail Use% Mounted on
/dev/mapper/ol-root   36G  4.0G   32G  12% /
devtmpfs             1.8G     0  1.8G   0% /dev
tmpfs                1.8G     0  1.8G   0% /dev/shm
tmpfs                1.8G  8.9M  1.8G   1% /run
tmpfs                1.8G     0  1.8G   0% /sys/fs/cgroup
/dev/sda1            497M  195M  303M  40% /boot
tmpfs                369M     0  369M   0% /run/user/0
/dev/sdb1             20G   45M   19G   1% /sdb
[root@localhost ~]# cd /sdb
[root@localhost sdb]# ls
99-sysctl.conf  lost+found
[root@localhost sdb]# more 99-sysctl.conf
# System default settings live in /usr/lib/sysctl.d/00-system.conf.
# To override those settings, enter new settings here, or in an /etc/sysctl.d/<name>.conf file
#
# For more information, see sysctl.conf(5) and sysctl.d(5).

ext4文件系统修复

[root@localhost ~]# mkfs.ext3 /dev/sdb1
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1310720 inodes, 5242624 blocks
262131 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
160 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000

Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

[root@localhost ~]# mount /dev/sdb1 /sdb
[root@localhost ~]# df -h
Filesystem           Size  Used Avail Use% Mounted on
/dev/mapper/ol-root   36G  4.0G   32G  12% /
devtmpfs             1.8G     0  1.8G   0% /dev
tmpfs                1.8G     0  1.8G   0% /dev/shm
tmpfs                1.8G  8.9M  1.8G   1% /run
tmpfs                1.8G     0  1.8G   0% /sys/fs/cgroup
/dev/sda1            497M  195M  303M  40% /boot
tmpfs                369M     0  369M   0% /run/user/0
/dev/sdb1             20G   45M   19G   1% /sdb
[root@localhost ~]# dd if=/dev/zero of=/dev/sdb1 bs=1024 count=5
5+0 records in
5+0 records out
5120 bytes (5.1 kB) copied, 0.0138915 s, 369 kB/s
[root@localhost ~]# fsck -t ext3 /dev/sdb1
fsck from util-linux 2.23.2
e2fsck 1.42.9 (28-Dec-2013)
ext2fs_open2: Bad magic number in super-block
fsck.ext3: Superblock invalid, trying backup blocks...
/dev/sdb1 was not cleanly unmounted, check forced.
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information

/dev/sdb1: ***** FILE SYSTEM WAS MODIFIED *****
/dev/sdb1: 11/1310720 files (0.0% non-contiguous), 126322/5242624 blocks
[root@localhost ~]# mount /dev/sdb1 /sdb
[root@localhost ~]# df -h
Filesystem           Size  Used Avail Use% Mounted on
/dev/mapper/ol-root   36G  4.0G   32G  12% /
devtmpfs             1.8G     0  1.8G   0% /dev
tmpfs                1.8G     0  1.8G   0% /dev/shm
tmpfs                1.8G  8.9M  1.8G   1% /run
tmpfs                1.8G     0  1.8G   0% /sys/fs/cgroup
/dev/sda1            497M  195M  303M  40% /boot
tmpfs                369M     0  369M   0% /run/user/0
/dev/sdb1             20G   45M   19G   1% /sdb

fsck修复危险性较大,建议先备份对应的分区(dd命令备份分区)然后再处理,有导致分区数据全部或者部分丢失的风险,如果超级块彻底损坏无法恢复,请联系我们，提供专业ORACLE数据库恢复技术支持
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