Installed Ubuntu on Old laptop for testing new thing like Docker. met 2 issue.

Issue 1. Update the disk partition table caused the grub confused.

I have 4 slice of my harddisk, /dev/sda1 for Windows. /dev/sda5 for windows 2nd partition. /dev/sda6 for Ubuntu./dev/sda7 for Ubuntu swap.

when I need more space for linux, I remove /dev/sda5. then /dev/sda6 become /dev/sda5 …. that confused grub. because grub still hold the record /dev/sda6 is the linux partition.

Fix: grub rescue>ls

grub rescue>set

change the prefix and the root from (hd0,msdos6) to (hd0,msdos5)

grub rescue>insmod /boot/grub/i386-pc/normal.mod

grub rescue>normal

Then you got my grub back , boot into Ubuntu and then run sudo update-grub2 , grub.cfg should be updated.

Issue 2. Apparmor issue, when I try to migrate mysql data to /data/mysql. found the mysql won’t start

it keeps complains:

/usr/sbin/mysqld: Can’t find file: ‘./mysql/plugin.frm’ (errno: 13)

141207 17:02:29 [ERROR] Can’t open the mysql.plugin table. Please run mysql_upgrade to create it.

141207 17:02:29 InnoDB: The InnoDB memory heap is disabled


InnoDB: The error means mysqld does not have the access rights to

InnoDB: the directory.

InnoDB: File name ./ibdata1

InnoDB: File operation call: ‘open’.

InnoDB: Cannot continue operation.

finally turn out it’s Apparmor which like SElinux.

sudo apparmor_status


Fix: add the data directory to the apparmor policy file.


/data/mysql/ r,

/data/mysql/** rwk,