# e4defrag cannot find the ext4 superblock

## hsgg

Hi,

e4defrag is in sys-fs/e2fsprogs-1.42_pre0702. Hooray. I have two ext4 partitions on my setup: the root, and /home. Using e4defrag anywhere on /home works very nicely, but on the root partition it just says:

```

# e4defrag -v -c /

Can't get super block info: No such file or directory

 "/"

```

I don't have any other problems with the root partition. Running fsck on boot doesn't report any errors, tune2fs does find the superblock, and it doesn't report any problems either afaics:

```

# tune2fs -l /dev/sda3

tune2fs 1.42-WIP (02-Jul-2011)

Filesystem volume name:   Gentoo

Last mounted on:          /

Filesystem UUID:          e68df512-98b9-4561-8456-4b99611d3319

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:              2596864

Block count:              10375981

Reserved block count:     518799

Free blocks:              2376877

Free inodes:              1712059

First block:              0

Block size:               4096

Fragment size:            4096

Reserved GDT blocks:      1021

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 May 10 00:49:54 2011

Last mount time:          Fri Dec  2 14:01:35 2011

Last write time:          Mon Nov 28 18:01:57 2011

Mount count:              5

Maximum mount count:      25

Last checked:             Mon Nov 28 18:01:57 2011

Check interval:           15552000 (6 months)

Next check after:         Sat May 26 19:01:57 2012

Lifetime writes:          391 GB

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:      4ac73895-d6dd-4c2a-badf-8d8ef528689c

Journal backup:           inode blocks

```

There is no "Raid stride" given (as opposed to what is reported for /home). Does that matter?

I converted the filesystem from ext3 to ext4 sometime in 2009. Maybe something didn't go quite right back then. Short of trying to reformat, is there anything else I can try?

As I am not having any other issues, this is not of priority. I just wanted to see if e4defrag can lower my boot time. I am open to suggestions.

Thanks,

Henry

PS: I should probably note that I am using ~amd64 and systemd.

----------

## Soichiro

Bump. I wanted to bring this thread back to the top because I'm experience the same issue, with e2fsprogs-1.42.5. I can defragment my /boot partition with no problems, but not my root partition.

```
tune2fs 1.42.5 (29-Jul-2012)

Filesystem volume name:   <none>

Last mounted on:          /

Filesystem UUID:          bd1f5bdc-517a-4f8a-bab9-d226c0ab46eb

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:    user_xattr acl

Filesystem state:         clean

Errors behavior:          Continue

Filesystem OS type:       Linux

Inode count:              4423680

Block count:              17667108

Reserved block count:     883355

Free blocks:              12341371

Free inodes:              4005500

First block:              0

Block size:               4096

Fragment size:            4096

Reserved GDT blocks:      1019

Blocks per group:         32768

Fragments per group:      32768

Inodes per group:         8192

Inode blocks per group:   512

Flex block group size:    16

Filesystem created:       Fri Aug 10 20:03:53 2012

Last mount time:          Sun Aug 12 02:38:52 2012

Last write time:          Sun Aug 12 02:38:52 2012

Mount count:              3

Maximum mount count:      -1

Last checked:             Fri Aug 10 20:03:53 2012

Check interval:           0 (<none>)

Lifetime writes:          32 GB

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

First orphan inode:       1052758

Default directory hash:   half_md4

Directory Hash Seed:      67f7b003-859d-4ec3-870a-c865e87a94c5

Journal backup:           inode blocks

```

----------

## hsgg

A few weeks ago I found a solution. e4defrag looks for your root partition at whatever "mount" and "df" report for it, probably /dev/root, but that doesn't exist. So

```
# ln -s /dev/sda3 /dev/root
```

where sda3 should be the device name of your root partition should fix it. HTH.

----------

## Soichiro

Thank you, that worked!  :Very Happy: 

----------

