No Journaling Ext4?

[Chemical Imbalance]

I have an eeepc with an ssd that I want to help preserve by turning off journaling in Jaunty on my ext4 partition.

I have found some documentation which says the option to mount it as writeback (nonjournaling) mode is

data=writeback

Which I'm assuming you add to the defaults line in fstab.

I've tried adding this and each time I get a read-only partition (due to a default setting in fstab that upon errors mounts read-only) and an Xorg failure to load.

I have to load a livesession to edit my fstab back.



Can anybody help me figure out why this is mounting with errors? Do I have to apply a patch to allow writeback mode? What am I doing wrong?

[dcstar]

I have an eeepc with an ssd that I want to help preserve by turning off journaling in Jaunty on my ext4 partition.
.......

http://ubuntuforums.org/showthread.php?t=1063499

[hyper_ch]

I wouldn't use Ext4 yet...

[Chemical Imbalance]

I wouldn't use Ext4 yet...

I realize the risk, I just want a solution.

Data loss isn't a big issue on this 4gb ssd for me :)

I just use it for internet surfing and small tasks. The boot up time is very much improved with ext4

[Chemical Imbalance]

I came across someone mentioning that one has to upgrade to a newer kernel to get this functionality. I guess solved.

[rsambuca]

I came across someone mentioning that one has to upgrade to a newer kernel to get this functionality. I guess solved.

Do you know which kernel version you need for this?

[Yashiro]

If you're going to disable journalling you might as well use ext2.

[Kow]

The 2.6.29 kernel supports ext4 w/o a journal.

[rsambuca]

If you're going to disable journalling you might as well use ext2.

Wrong.

If you read the ext4 kernel developers mailings, ext4 without a journal is much quicker than ext2, and with many other benefits.

[Yashiro]

Along with much less testing and real world use.

[vahnx]

I'm using ext4 and it's blazing fast and working fine for me :D

[antistress]

Data Mode
=========
There are 3 different data modes:

* writeback mode
In data=writeback mode, ext4 does not journal data at all. This mode provides a similar level of journaling as that of XFS, JFS, and ReiserFS in its default mode - metadata journaling. A crash+recovery can cause incorrect data to appear in files which were written shortly before the crash. This mode will typically provide the best ext4 performance.

* ordered mode
In data=ordered mode, ext4 only officially journals metadata, but it logically groups metadata information related to data changes with the data blocks into a single unit called a transaction. When it's time to write the new metadata out to disk, the associated data blocks are written first. In general, this mode performs slightly slower than writeback but significantly faster than journal mode.

* journal mode
data=journal mode provides full data and metadata journaling. All new data is written to the journal first, and then to its final location.
In the event of a crash, the journal can be replayed, bringing both data and
metadata into a consistent state. This mode is the slowest except when data
needs to be read from and written to disk at the same time where it outperforms all others modes. Curently ext4 does not have delayed allocation support if this data journalling mode is selected.

http://www.mjmwired.net/kernel/Documentation/filesystems/ext4.txt#313

[Chemical Imbalance]

Data Mode
=========
There are 3 different data modes:

* writeback mode
In data=writeback mode, ext4 does not journal data at all. This mode provides a similar level of journaling as that of XFS, JFS, and ReiserFS in its default mode - metadata journaling. A crash+recovery can cause incorrect data to appear in files which were written shortly before the crash. This mode will typically provide the best ext4 performance.

* ordered mode
In data=ordered mode, ext4 only officially journals metadata, but it logically groups metadata information related to data changes with the data blocks into a single unit called a transaction. When it's time to write the new metadata out to disk, the associated data blocks are written first. In general, this mode performs slightly slower than writeback but significantly faster than journal mode.

* journal mode
data=journal mode provides full data and metadata journaling. All new data is written to the journal first, and then to its final location.
In the event of a crash, the journal can be replayed, bringing both data and
metadata into a consistent state. This mode is the slowest except when data
needs to be read from and written to disk at the same time where it outperforms all others modes. Curently ext4 does not have delayed allocation support if this data journalling mode is selected.

http://www.mjmwired.net/kernel/Documentation/filesystems/ext4.txt#313

I already knew this, thanks though

And the question has been solved, writeback mode can only be enabled in the 2.6.29 kernal AFAIK

[KhaaL]

I already knew this, thanks though

And the question has been solved, writeback mode can only be enabled in the 2.6.29 kernal AFAIK

can you tell me if this is a correct way to disable the journal in ext4:

UUID=04cfdee9-af03-44c1-b313-71e328fa174e / ext4 data=writeback,errors=remount-ro 0 0

Because like you, i had trouble enabling it and i got onto a read-only filesystem.

Tip: if you want even faster performance add the noatime,nodiratime switches in fstab ;)

[Chemical Imbalance]

can you tell me if this is a correct way to disable the journal in ext4:

UUID=04cfdee9-af03-44c1-b313-71e328fa174e / ext4 data=writeback,errors=remount-ro 0 0

Because like you, i had trouble enabling it and i got onto a read-only filesystem.

Tip: if you want even faster performance add the noatime,nodiratime switches in fstab ;)

Like I said, you need the .29 kernel, so I guess you will have to compile one.

I already use noatime instead of relatime, but what does nodiratime do?

[KhaaL]

no need to compile, you can get one from here: http://kernel.ubuntu.com/~kernel-ppa/mainline/

nodiratime turns off updates for folders, but i think that noatime includes that (can someone confirm?)

[Chemical Imbalance]

no need to compile, you can get one from here: http://kernel.ubuntu.com/~kernel-ppa/mainline/

nodiratime turns off updates for folders, but i think that noatime includes that (can someone confirm?)

Ahhh, thanks for the link! I didn't realize there were debs available

It sounds like nodiratime is a bit extreme. I don't think folder updates would affect performance that much, do you?

[KhaaL]

noatime is more extreme than nodiratime since it disables for the whole filesystem, IMO if you're disabling accesstime for files you might aswell do it for directories :) I use that switch to keep HD writes to a miminum since I'm affected by a kernel bug that puts my computer to a standstill when there is HD activity.

[Kow]

I already knew this, thanks though

And the question has been solved, writeback mode can only be enabled in the 2.6.29 kernal AFAIK

Are you sure? Via "tune2fs -o journal_data_writeback <device>" with ubuntu's 2.6.28 kernel I get this when EXT4 is mounted:

"[ 3.305576] EXT4-fs: mounted filesystem with writeback data mode."

Perhaps this is lying to me until 2.6.29?

[Chemical Imbalance]

Are you sure? Via "tune2fs -o journal_data_writeback <device>" with ubuntu's 2.6.28 kernel I get this when EXT4 is mounted:

"[ 3.305576] EXT4-fs: mounted filesystem with writeback data mode."

Perhaps this is lying to me until 2.6.29?

I guess I heard wrong...why does everyone have to be so smart-*ssed?

It didn't work for me or the op in this thread.

Please tell us exactly what you did...

[Jordanwb]

This thread is relevant to my interests. When I make an ext4 filesystem is makes a journal even if you don't want one. Is it possible to tell it not to make a journal?

[Sarvatt]

You need to change the journaling option with tune2fs instead of through fstab, it mounts the partition through grub first and then remounts it rw through fstab but its too late to change journaling type by that point. the same problem exists for changing the journaling type on ext3 in fstab.

[weeman7007]

You need to change the journaling option with tune2fs instead of through fstab, it mounts the partition through grub first and then remounts it rw through fstab but its too late to change journaling type by that point. the same problem exists for changing the journaling type on ext3 in fstab.

how would I do that?

[Jordanwb]

how would I do that?

I've never used tune2fs but I would guess:

tune2fs /dev/sda1 -o data=writeback

The man page for tune2fs reports it works only on ext2/3 FS's.

[sgosnell]

I'm not sure why everyone is so concerned with wearing out the SSD. The EEE will be long obsolete before you could possibly wear out the SSD, even with constant writes. Boooooguuuusssssssssssssssss.

[Kow]

I guess I heard wrong...why does everyone have to be so smart-*ssed?

It didn't work for me or the op in this thread.

Please tell us exactly what you did...

sudo tune2fs -o journal_data_writeback /dev/whatever

Replace 'whatever' with your hard disk 3 letter abbrev and the partition (ex: /dev/sda1) After that, reboot. But, this is NOT running ext4 without a journal. Per tune2fs manpage:

When the filesystem is mounted with journalling
enabled, data may be written into the main filesys‐
tem after its metadata has been committed to the
journal. This may increase throughput, however, it
may allow old data to appear in files after a crash
and journal recovery.

[Chemical Imbalance]

I'm not sure why everyone is so concerned with wearing out the SSD. The EEE will be long obsolete before you could possibly wear out the SSD, even with constant writes. Boooooguuuusssssssssssssssss.

Some of us are more cautious (read: paranoid) then others :).

I guess with my cheap and slow ssd an SD-card might be an upgrade if it ever wears out :lolflag:

[Sarvatt]

how would I do that?

tune2fs -O ^has_journal /dev/sd?

no idea if it'll cause problems though.

[charcer]

I'm also interested in ext4 without journal for my acer aspire one with ssd drive.
At the moment I have xubuntu 9.04 beta with kernel 2.6.29.1

First I booted to xubuntu live usb-disk and run
tune2fs -O ^has_journal /dev/sda1

It gave no errors, but when rebooted the laptop gave me initramfs prompt, and a message "Alert! /dev/disk/by-uuid/xxxxxxxx does not exist. Dropping to a shell!"
It was the same with kernel .28 and with safe modes.

The I booted to live disk again, and run
tune2fs -O has_journal /dev/sda1

which reverted the situation, and I was able to boot again.


Lastly I booted to live disk and run
sudo tune2fs -o journal_data_writeback /dev/sda1

and that seemed to work in a way that there wasn't any errors and I could boot normally.


But I'm still curious if that's the right method, is there some way I can check if a journal exists?
And also does /fstab need any special mount options when i have run the tune2fs -o journal_data_writeback command?

[Sarvatt]

I'm also interested in ext4 without journal for my acer aspire one with ssd drive.
At the moment I have xubuntu 9.04 beta with kernel 2.6.29.1

First I booted to xubuntu live usb-disk and run
tune2fs -O ^has_journal /dev/sda1

It gave no errors, but when rebooted the laptop gave me initramfs prompt, and a message "Alert! /dev/disk/by-uuid/xxxxxxxx does not exist. Dropping to a shell!"
It was the same with kernel .28 and with safe modes.

The I booted to live disk again, and run
tune2fs -O has_journal /dev/sda1

which reverted the situation, and I was able to boot again.


Lastly I booted to live disk and run
sudo tune2fs -o journal_data_writeback /dev/sda1

and that seemed to work in a way that there wasn't any errors and I could boot normally.


But I'm still curious if that's the right method, is there some way I can check if a journal exists?
And also does /fstab need any special mount options when i have run the tune2fs -o journal_data_writeback command?

you should have to e2fsck manually before rebooting to remove the journal..

sudo dumpe2fs /dev/sdawhatever shows the info

ext4 should mount writeback by default on 2.6.29.

it might actually need an update to e2fsprogs before you can do it looking at the git repo.

http://git.kernel.org/?p=fs/ext2/e2fsprogs.git;a=shortlog

http://git.kernel.org/?p=fs/ext2/e2fsprogs.git;a=commit;h=a90f5391dda78f7bc4a8196a7 8355584ace0adf5