From ext3 to ext4

rengo.Java · 12-26-2008, 04:15 PM

Hi all!
I hear that ext4 is stable in the 2.6.28 kernel.
I download it and compile it whit ext4 support.

Now, what is the best way to migrate the ext3 partitions to ext4.
Is enough with mounting the partitions using the ext4 filesystem type? in this way i have all the adventages of ext4 like extents?? Or I must to format or run some command to migrate??
And can I use ext4 in my root partition (and boot from it with LILO)?

I read a lot of articles and Im confused about this...

Thanks!!

harry edwards · 12-26-2008, 04:19 PM

Does this help: http://www.ibm.com/developerworks/li...xt4/index.html it seems all you have to do it mount using the new type.

rengo.Java · 12-26-2008, 04:26 PM

Quote:

To use a device as an ext4 file system, you should mount it with the ext4dev file system type code. (When ext4 becomes stable, the file system type code will change to ext4.) For instance, mount -t ext4dev /dev/sda6 /mnt/point mounts /dev/sda6 as an ext4 file system at /mnt/point. That's all there is to basic ext4 use. Be aware that the default mount options enable extents, which renders the file system unusable as an ext3 file system. If you want to try ext4 but retain the option of going back to ext3, use the -o noextents option to disable use of extents.

Thanks!!

syg00 · 12-26-2008, 06:49 PM

Have a look at ext4.txt in your source tree - it will refer you to the ext4 wiki. Spend some time there.

i92guboj · 12-26-2008, 08:14 PM

Quote:

Originally Posted by harry edwards

Does this help: http://www.ibm.com/developerworks/li...xt4/index.html it seems all you have to do it mount using the new type.

That will work, but just mounting it as the new type will not provide ALL the ext4 new capabilities.

Check this,

http://kernelnewbies.org/Ext4

all the procedures are described there. The full conversion involves using tune2fs to turn on the new capabilities, and fsck to apply all the changes so it can be mounted as ext4.

rengo.Java · 12-27-2008, 06:37 AM

Quote:

Originally Posted by syg00

Have a look at ext4.txt in your source tree - it will refer you to the ext4 wiki. Spend some time there.

There is a thing I dont understand

Quote:

Or configure an existing ext3 filesystem to support extents and set
the test_fs flag to indicate that it's ok for an in-development
filesystem to touch this filesystem:

# tune2fs -O extents -E test_fs /dev/hda1

When I do this step, the filesystem to be converted, must be unmounted? I think yes, but unsure...

Thanks for the answers!

dhave · 12-27-2008, 09:58 AM

Quote:

Originally Posted by rengo.Java

There is a thing I dont understand

When I do this step, the filesystem to be converted, must be unmounted? I think yes, but unsure...

Thanks for the answers!

Yes, to run the tune2fs command, the target filesystem must be unmounted. This means you may have to boot from a LiveCD, depending on which partition you plan to convert.