问题情况     500G机械硬盘使用过程中出现挂载失败的问题，查看是第二分区没有挂载，进行分析与排查； 查看磁盘 Disk /dev/sdb: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 1 244 1959898+ 83 Linux /dev/sdb2 245 60801 486424102+ 83 Linux     容量和分区正常； 查看挂载 /dev/sdb1 1.8G 5.6M 1.7G 0% /extroot/mini_web /dev/sdb1 on /extroot/mini_web type ext4 (ro,nosuid,nodev,noatime,nodelalloc,journal_checksum,noauto_da_alloc,data=ordered)     第一分区挂载容量和挂载正常；     第2分区没有挂载成功，下面尝试挂载和修复； 无参挂载 ~ # mount /dev/sdb2 aa EXT4-fs (sdb2): error loading journal EXT4-fs (sdb2): couldn't mount as ext3 due to feature incompatibilities EXT4-fs (sdb2): couldn't mount as ext2 due to feature incompatibilities JBD2: journal transaction 107652 on sdb2-8 is corrupt. EXT4-fs (sdb2): error loading journal yaffs: dev is 8388626 name is "sdb2" rw yaffs: passed flags "" yaffs: yaffs: Attempting MTD mount of 8.18,"sdb2" yaffs: yaffs: MTD device 18 either not valid or unavailable yaffs: dev is 8388626 name is "sdb2" rw yaffs: passed flags "" yaffs: yaffs: Attempting MTD mount of 8.18,"sdb2" yaffs: yaffs: MTD device 18 either not valid or unavailable     ext2/3/4和yaffs2都挂载失败，第二分区是ext4文件系统，挂载失败，提示文件日志加载失败，可能是被破坏； 尝试修复 fsck.ext4 /dev/sdb2 -yf     修复时提示很多文件被破坏，在lost-found目录下很多文件，看来文件损坏很严重，查看是否硬件掉电次数为0，文件被破坏原因未知待查； 重新挂载 mount -t ext4 /dev/sdb2 aa /dev/sdb2 462.7G 104.4G 335.1G 24% /tmp/aa /dev/sdb2 on /tmp/aa type ext4 (rw,relatime,data=ordered)     重新挂载成功 总结     使用过程中文件被破坏，挂载失败后应该尝试进行后台修复；文件被破坏原因待查。