# system trying to mount my root file system as the wrong type

## LTsix

So I'm seeing this odd error is this udev doing something funny? Is it a bug. I noticed that the system is trying to mount my root file system as ext3 then tries ext2 then uses the fstab and does ext4....

```
[    8.701290] usb usb5: suspend_rh

[    8.741494] EXT3-fs: sda3: couldn't mount because of unsupported optional features (240).

[    8.784493] EXT2-fs: sda3: couldn't mount because of unsupported optional features (240).

[    8.838121] EXT4-fs: barriers enabled

[    8.875428] kjournald2 starting: pid 996, dev sda3:8, commit interval 5 seconds

[    8.875496] EXT4-fs: delayed allocation enabled

[    8.875500] EXT4-fs: file extents enabled

[    8.882574] EXT4-fs: mballoc enabled

[    8.882578] EXT4-fs: mounted filesystem sda3 with ordered data mode

[    8.882601] VFS: Mounted root (ext4 filesystem) readonly on device 8:3.
```

My fstab.

```
# /etc/fstab: static file system information.

#

# noatime turns off atimes for increased performance (atimes normally aren't 

# needed; notail increases performance of ReiserFS (at the expense of storage 

# efficiency).  It's safe to drop the noatime options if you want and to 

# switch between notail / tail freely.

#

# The root filesystem should have a pass number of either 0 or 1.

# All other filesystems should have a pass number of 0 or greater than 1.

#

# See the manpage fstab(5) for more information.

#

# <fs>         <mountpoint>   <type>      <opts>      <dump/pass>

# NOTE: If your BOOT partition is ReiserFS, add the notail option to opts.

/dev/sda1      /boot      ext2      noauto,noatime   1 2

/dev/sda3      /      ext4      noatime      0 1

/dev/sda2      none      swap      sw      0 0

#/dev/cdrom      /mnt/cdrom   auto      noauto,ro   0 0

#/dev/fd0      /mnt/floppy   auto      noauto      0 0

# glibc 2.2 and above expects tmpfs to be mounted at /dev/shm for 

# POSIX shared memory (shm_open, shm_unlink).

# (tmpfs is a dynamically expandable/shrinkable ramdisk, and will

#  use almost no memory if not populated with files)

shm         /dev/shm   tmpfs      nodev,nosuid,noexec   0 0
```

Let me know what everyone thinks.

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## judepereira

It's perfectly fine as even i use ext4 and the same thing pops up during my system boot.

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## LTsix

Yeah, but I think that this could be an issue. As the system is not using your fstab first and then guessing. What would occur if someone added the extents flag to a ext3 part or something. I just think there is a potential for major issues. I'm not doubting that my computer will work fine but you never know how someone can manage to break something.

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## eccerr0r

When kernel is initializing the root filesystem, there's no way for it to know what you have in your /etc/fstab...  To make it easier to get computers going, it has to autodetect...  You can remount it later; ideally the best solution for this case is to use initrd.

It looks like it's trying ext3 first, then ext2.  I'm not sure about the backward compatibility of ext4 but it looks like it may be doing the right thing in this case, detecting a ext2/3 disk but having extra features and skipping for hopes that ext4 will pick up these features...

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## gentoo_ram

The root filesystem is not mounted according to /etc/fstab, it's mounted by the kernel during the boot process.  If you want your filesystem to be mounted as ext4 at boot, add the command line parameter "rootfstype=ext4" to the kernel command line.  This is documented in /usr/src/linux/Documentation/kernel-parameters.txt

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