** Description changed:
Symptoms: (Ubuntu 9.10 on an ext4 partition /dev/sda1)
1. Booting fails.
2. mount /dev/sda1 /mnt gives mount: you must specify the filesystem
type
but mount -t ext4 /dev/sda1 is successful
3. blkid /dev/sda1 returns nothing
4. blkid -p /dev/sda1 gives ambivalent result (probably more
filesystems on the device)
After installing util-linux-ng-2.17 from source:
5. wipefs /dev/sda1 returns:
offset type
0x410minix [filesystem]
0x438ext4 [filesystem]
UUID: d3bb8e26-9798-49ce-bc57-afb6ca62a7ba
I was able to cure the problem by creating a file on /dev/sda1 and
whereby changing the number of free inodes. There have been six of these case
in the Ubuntu forums by now:
http://ubuntuforums.org/showthread.php?t=1397193
http://ubuntuforums.org/showthread.php?t=1414662
http://ubuntuforums.org/showthread.php?t=1068895
My diagnosis:
- Minix uses the magic number 6824 at the location 0x410 to mark a
- Minix file system.
+ Minix uses the magic number 137f, 138f, 2468,2478, at the location
+ 0x410 to mark a Minix file system.
0x410 is also the location any ext filesystem uses to record the number of
free inodes.
(The number of free inodes is essentially the number of files you are still
able to create on the file system)
- 9320 in little endian decoding is 6824
+ In decimals those four umbers are 4991,5007,9320,9336
- If the number of free inodes happens to be 9320 plus a multiple of
- 65536, then the ext filesystem will write 6824 to the 0x410
- location.
+ If the number of free inodes happens to be one of those four numbers
+ plus a multiple of 65536, then the ext filesystem will write one of
+ the four Minix magic numbers to the 0x410 location.
- So many programs will gets confused and don't know whether the files
- system is Minix or Ext.
+ So many programs will gets confused and don't know whether the files system
is Minix or Ext.
+ In particular, if this happens on the root partition, Ubuntu will no longer
boot.
** Description changed:
Symptoms: (Ubuntu 9.10 on an ext4 partition /dev/sda1)
1. Booting fails.
2. mount /dev/sda1 /mnt gives mount: you must specify the filesystem
type
but mount -t ext4 /dev/sda1 is successful
3. blkid /dev/sda1 returns nothing
4. blkid -p /dev/sda1 gives ambivalent result (probably more
filesystems on the device)
After installing util-linux-ng-2.17 from source:
5. wipefs /dev/sda1 returns:
offset type
0x410minix [filesystem]
0x438ext4 [filesystem]
UUID: d3bb8e26-9798-49ce-bc57-afb6ca62a7ba
I was able to cure the problem by creating a file on /dev/sda1 and
whereby changing the number of free inodes. There have been six of these case
in the Ubuntu forums by now:
http://ubuntuforums.org/showthread.php?t=1397193
http://ubuntuforums.org/showthread.php?t=1414662
http://ubuntuforums.org/showthread.php?t=1068895
My diagnosis:
Minix uses the magic number 137f, 138f, 2468,2478, at the location
0x410 to mark a Minix file system.
- 0x410 is also the location any ext filesystem uses to record the number of
free inodes.
- (The number of free inodes is essentially the number of files you are still
able to create on the file system)
+ 0x410 is also the location any ext filesystem uses to record the number
+ of free inodes.
In decimals those four umbers are 4991,5007,9320,9336
If the number of free inodes happens to be one of those four numbers
plus a multiple of 65536, then the ext filesystem will write one of
the four Minix magic numbers to the 0x410 location.
So many programs will gets confused and don't know whether the files system
is Minix or Ext.
In particular, if this happens on the root partition, Ubuntu will no longer
boot.
** Description changed:
Symptoms: (Ubuntu 9.10 on an ext4 partition /dev/sda1)
1. Booting fails.
2. mount /dev/sda1 /mnt gives mount: you must specify the filesystem
type
but mount -t ext4 /dev/sda1 is successful
3. blkid /dev/sda1 returns nothing
4. blkid -p /dev/sda1 gives ambivalent result (probably more
filesystems on the device)
+ 5. hexdump -s 0x410 -n 2 /dev/sda1 returns on of the four numbers
+ hexadecimals 137f, 138f, 2468,2478,
+
After installing util-linux-ng-2.17 from source:
- 5. wipefs /dev/sda1 returns:
+ 6. wipefs /dev/sda1 returns:
offset type
0x410minix [filesystem]
0x438ext4
