1 ext4格式lv扩展。扩展之前忘记umount，导致e2fscheck出错（红字部分）
[root@localhost ~]# blkid | grep vo
/dev/mapper/juanzu-vo: UUID="3e376bb6-d29a-4e7b-8ad4-fe0968d5f1a6" TYPE="ext4"
[root@localhost ~]# 忘记umount
[root@localhost ~]# lvextend -L 300M /dev/juanzu/vo
Extending logical volume vo to 300.00 MiB
Logical volume vo successfully resized
[root@localhost ~]# e2fsck -f /dev/juanzu/vo
e2fsck 1.42.9 (28-Dec-2013)
/dev/juanzu/vo is mounted.
e2fsck: Cannot continue, aborting.
[root@localhost ~]# umount /dev/juanzu/vo
[root@localhost ~]#
[root@localhost ~]# e2fsck -f /dev/juanzu/vo
e2fsck 1.42.9 (28-Dec-2013)
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/juanzu/vo: 11/20480 files (9.1% non-contiguous), 8240/81920 blocks
[root@localhost ~]#
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解决办法：
1，reboot无效
2，OK
刘 2018/12/17 15:34:01
数据没有丢失就行
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2 设置crond开机启动时，是否考虑登录哪个账户？比如在root时设置开机启动，那在用户natasha账户内的crond任务是否也会开机启动？
[root@station tmp]# crontab -e -u natasha
#root账户下编辑natasha用户的crond任务
no crontab for natasha - using an empty one
crontab: installing new crontab
[root@station tmp]# crontab -l -u natasha
23 14 * * * /bin/echo hiya
[root@station tmp]#
[root@station tmp]# systemctl restart crond.service
[root@station tmp]# systemctl enable crond.service
#root账户下设置crond开机启动。那么上面新建的natasha账户的crond任务是否会在开机时自动启动？
[root@station tmp]#
[root@station tmp]# su - natasha
[natasha@station ~]$ systemctl restart crond.service
Failed to issue method call: Access denied
[natasha@station ~]$
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解决方法：
reboot后发现root和natasha账户的crond都是开机启动的。
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