I'm running the lastest Ubuntu 12.04 AMI (ami-a29943cb) from Canonical on Amazon EC2 and quite often when I log in I get the message:

*** /dev/xvda1 will be checked for errors at next reboot ***

I have read a bunch of documentation on this and seem to understand that every so many reboots (around 37 see Mount count / Maximum mount count below) Ubuntu wants to check a disk for errors. I can see that by using dumpe2fs -h /dev/xvda1 (reference) to get information such as:

Last mounted on:          /

Filesystem UUID:          1ad27d06-4ecf-493d-bb19-4710c3caf924

Filesystem magic number:  0xEF53

Filesystem revision #:    1 (dynamic)

Filesystem features:      has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize

Filesystem flags:         signed_directory_hash 

Default mount options:    (none)

Filesystem state:         clean

Errors behavior:          Continue

Filesystem OS type:       Linux

Inode count:              524288

Block count:              2097152

Reserved block count:     104857

Free blocks:              1778055

Free inodes:              482659

First block:              0

Block size:               4096

Fragment size:            4096

Reserved GDT blocks:      511

Blocks per group:         32768

Fragments per group:      32768

Inodes per group:         8192

Inode blocks per group:   512

Flex block group size:    16

Filesystem created:       Tue Apr 24 03:07:48 2012

Last mount time:          Thu Nov  8 03:17:58 2012

Last write time:          Tue Apr 24 03:08:52 2012

Mount count:              3

Maximum mount count:      37

Last checked:             Tue Apr 24 03:07:48 2012

Check interval:           15552000 (6 months)

Next check after:         Sun Oct 21 03:07:48 2012

Lifetime writes:          2454 MB

Reserved blocks uid:      0 (user root)

Reserved blocks gid:      0 (group root)

First inode:              11

Inode size:           256

Required extra isize:     28

Desired extra isize:      28

Journal inode:            8

Default directory hash:   half_md4

Directory Hash Seed:      0a25e04c-6169-4d68-bfa6-a1acd8e39632

Journal backup:           inode blocks

Journal features:         journal_incompat_revoke

Journal size:             128M

Journal length:           32768

Journal sequence:         0x0000158b

Journal start:            1

I've tried these things to get rid of the message and usually the badblocks is what does it for me:

Run this command and reboot:

sudo touch /forcefsck

Run badblocks to check the disk:

badblocks /dev/sda1

Edit /etc/fstab and change the last "0" which is the fs_passno column accordingly and then reboot:

The root filesystem should be specified with a fs_passno of 1, and other filesystems should have a fs_passno of 2.

I don't understand:

1. If this is a virtual drive shouldn't it be less prone to errors?


2. Was the image created with one of the flags set? If not what is triggering it?


3. Why is fs_passno set to 0 on Amazon EC2 Ubuntu images? This is not the first one that is like this.