jbd2 causing a lot of disk access

Symptom: jbd2 very active in iotop:

  221 be/3 root        0.00 B/s   60.87 K/s  0.00 % 38.90 % [jbd2/sda2-8]

This can happen if you changed a lot of files on your hard disk, but activity will go lower over time.

To disable the updatedb cron that uses jbd2 also, you can do:

sudo chmod -x /etc/cron.daily/mlocate

You can also change the commit frequency in /etc/fstab (but jbd2 will happen anyway, but less frequently)

 root@arau3:~# more /etc/fstab 

# /etc/fstab: static file system information.

#

# Use 'blkid' to print the universally unique identifier for a

# device; this may be used with UUID= as a more robust way to name devices

# that works even if disks are added and removed. See fstab(5).

#

# <file system> <mount point>   <type>  <options>       <dump>  <pass>

# / was on /dev/sda2 during installation

UUID=d6852e87-0e39-44a1-a431-6f23456f1250 /               ext4    commit=60,errors=remount-ro 0      

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