Comments on: Linux Convert ext3 to ext4 File system

By: matter

matter — Fri, 08 Apr 2011 01:23:12 +0000

Another reference advised to run fsck.ext4 with -D after tune2fs:

fsck.ext4 -yfD /dev/sdc1

Linas also advised enabling extents on all files / directories which will save the trouble of copying things around in order to achieve the full ext4 benefit. I used this after mounting the partition:

find . -xdev -type f -print0 |\
while read -d $” FILE; do chattr +e “${FILE}”; done
find . -xdev -type d -print0 |\
while read -d $” DIR; do chattr +e “${DIR}”; done

Cheers!

By: treah blade

treah blade — Mon, 17 May 2010 02:07:29 +0000

“How do I boot from ext4 (/boot)?”

The info in this section is incorrect please do not use. See the grub wiki for correct details on how to modify a grub2 boot files.

By: James Buergel

James Buergel — Mon, 04 Jan 2010 08:07:57 +0000

Any more good web sites on ext 4 and or the new grub 2 ?

By: Olivier

Olivier — Fri, 27 Nov 2009 20:56:09 +0000

I don’t understand why people are using ext3 or ext4 for /boot. Isn’t ext2 good enough ? Why the journaling would be useful for this partition ?

By: hooborg

hooborg — Mon, 26 Oct 2009 10:30:58 +0000

Hi,
In Redhat and Fedora there is /etc/grub.conf or /boot/grub/grub.conf not /boot/grub.conf (in How do I boot from ext4 (/boot)?)

By: brijesh

brijesh — Thu, 10 Sep 2009 13:56:24 +0000

sir
i want to know depth of linux file system can you provide me detail matter..
i am very much thankfull to you.
your faithfully
brijesh kumar
allahabad (india)

By: Joachim Otahal

Joachim Otahal — Thu, 21 May 2009 10:38:26 +0000

If you “convert” from ext3 to ext4 only new created files are “true” ext4, the existing files are still ext3-like, so existing files are as slow as usual, and deleting those files is as slow as usual too.
Use fresh formatted ext4 or copy the files around (not move inside one partition!) will help.

By: Drew

Drew — Wed, 06 May 2009 23:17:43 +0000

Oh yeah, when you reboot it seems to break a couple of desktop applets such as Quicklaunch (at least in my VM). And I did not notice an increase in boot times at all like so many have reported. Maybe it only applies to a fresh format ext4 w/ Ubuntu disc.

By: Joachim Otahal

Joachim Otahal — Sun, 26 Apr 2009 13:12:31 +0000

In case of Debian lenny: the fs-type must be “ext4dev” in fstab, since debian does not yet consider ext4 stable enough to call it “ext4″, that will probably make it in sid.

By: Shanker Jadapa

Shanker Jadapa — Thu, 05 Mar 2009 10:54:02 +0000

First time i heard about ext4 file system. thanks for the information

By: Prakash

Prakash — Wed, 25 Feb 2009 09:22:56 +0000

Ext4 users are reporting few problems :
http://ubuntuforums.org/showpost.php?p=6796365&postcount=251
and thread:
http://ubuntuforums.org/showthread.php?t=965879
–
Then ,we need e2fsprogs 1.41 or higher for ext4.kernel 2.6.28 for stable(eh?) ext4 unlike ext4dev.then converting a Linux root system from ext3 to ext4.Isn’t it risky with the current status of kernel support?

By: p-root

p-root — Tue, 27 Jan 2009 03:57:29 +0000

Great knowledge base that i ever found…….. :)

By: Vivek Gite

Vivek Gite — Sat, 24 Jan 2009 17:51:42 +0000

@ Peter / Alec

BobCFC is correct about defragmentation. This new feature is called online fragmentation. Right now it is *NOT* available in v2.6.28, but will be probably available in the next release. Quoting from ext4 wiki:

While delayed allocation, extents and multiblock allocation help to reduce the fragmentation, with usage filesystems can still fragment. For example: You write three files in a directory and continually on the disk. Some day you need to update the file of the middle, but the updated file has grown a bit, so there’s not enough room for it. You have no option but fragment the excess of data to another place of the disk, which will cause a seek, or allocate the updated file continually in another place, far from the other two files, resulting in seeks if an application needs to read all the files on a directory (say, a file manager doing thumbnails on a directory full of images). Besides, the filesystem can only care about certain types of fragmentation, it can’t know, for example, that it must keep all the boot-related files contiguous, because it doesn’t know which files are boot-related. To solve this issue, Ext4 will support online fragmentation, and there’s a e4defrag tool which can defragment individual files or the whole filesystem.

By: BobCFC

BobCFC — Sat, 24 Jan 2009 17:38:25 +0000

Thanks I am using Ext4 with Jaunty Alpha 3 as my main system for / and /home partitions (using the Alternated CD) and it is so fast I don’t even notice that I enabled encryption for the whole home directory. Now I can convert my data partitions too!

BTW I think the defrag feature refers to on-the-fly defragging while in use.

By: Alec

Alec — Sat, 24 Jan 2009 15:11:04 +0000

@ Peter:
I agree. File system fragmentation???
I’ve always enjoyed my linux clients and servers because I never had to schedule routine defragmentations like I have to do with Windows’ FAT and NTFS partitions…
I will have to look into this some and experement.
Thanks for the great post Vivek!

By: Peter

Peter — Sat, 24 Jan 2009 03:51:54 +0000

From your post it says a benefit of ext4 is Defragmentation support. What is happening here … I thought the benefit of linux file systems was that the files did not fragment ………. Are we about to see a flood of Windows style disk defragmenters?

By: Vivek Gite

Vivek Gite — Fri, 23 Jan 2009 22:08:57 +0000

@Daniel,

The post has been updated.

Appreciate your comment.

By: Daniel

Daniel — Fri, 23 Jan 2009 21:39:44 +0000

I just did this in Intrepid the other day, but took a different approach. You may want to advise your readers that Grub won’t boot to an ext4 partition. Since I have a separate /boot, I just converted my / to ext4 with no problems.

This is really simple actually, just requires a couple reboots:
sudo nano /etc/fstab
-change the fs type from ext3 to ext4dev for you root partition, the default options for ext4dev have extents enabled, so you cannot switch back to ext3
sudo touch /forcefsck
-this runs a fsck on reboot
sudo reboot
-let it run through the fsck, and once the system is up reboot again, it will need one more reboot and fsck to correct the journal
mount
-should list your partition as using ext4dev as the fs type