ext4 without journaling

[gabrielcik]

Hello,

I want to use the ext4 since i had problems with ext2.

I have a sdd and i heard it would be better to remove the journaling...

I found on the net this command for to remove it:
sudo tune2fs -O ^has_journal /dev/sdXN

is it safe? or maybe it is better to leave it on?

Thank you

[khelben1979]

If you feel uncertain, I would recommend to use the default settings of EXT4 or read the wiki document and see if it gives you something.

[dabl]

i had problems with ext2.

What does this mean -- what problems?

I cannot think of a "ext2 problem" that will be solved by using ext3 or ext4, except for the lack of a journal and extents.

[gabrielcik]

With ext2 it happens that after a simple crush (due to the gnome power control which didn't switch off the pc on low battery) the system didn't restart anymore.

In the same time with ext2, when the pc reboot after i update ubuntu packages the system restart making a file system check.

With ext4 journaled the restart is fine without any particular check...

Thank you

[Herman]

I have an SSD and I use ext4.

There was only ext2 and then file system journaling was added to make ext3.
If you remove or turn off the journaling you have ext2 and if you turn it on again you have ext3. (Basically speaking in simple terms).
Following are some interesting links for you to read if you want to know more details, Design and Implementation of the Second Extended Filesystem , EXT3, Journaling Filesystem , and Linux ext3 FAQ.

The new version of ext3 is called ext4 and it is excellent to use for SSD drive and all kinds of flash memory. Ext4 - kernelnewbies

Theodore Ts'o - Wikipedia link
Theodore Ts'o is the lead developer and maintainer of e2fsprogs and a maintainer of the ext4 file systems and he knows a lot about SSD drives too.
We are not 'left out in the cold', here is a link to blog he wrote on this subject, Archive for the ‘SSD’.

If you can spare the time, I recommend thoroughly studying all of those links and also the good quality sub-links those pages contain. There's a wealth of information there for you if you have the time to absorb it all.
I have been interested enough to read them all repeatedly myself. The short answer in my opinion is to use file system journaling, meaning we should use ext4 (with journaling).

[gabrielcik]

And what about to add noatime, is it really good for ssd?

[dabl]

With ext2 it happens that after a simple crush (due to the gnome power control which didn't switch off the pc on low battery) the system didn't restart anymore.

In the same time with ext2, when the pc reboot after i update ubuntu packages the system restart making a file system check.

With ext4 journaled the restart is fine without any particular check...

Thank you

You need to have the filesystem checked periodically, and especially after you lose power. It is not a bad thing that ext2 requires a filesystem check after a hard power-off. ext3 and ext4 also require a fsck after hard power-off.

The Ted Ts'o article recommends the noatime option on ext4 if you want to minimize disk writes.

[Herman]

And what about to add noatime, is it really good for ssd?

I think it's best to use noatime for installations in all kinds of flash memory, I think that Mr Ts'o probably knows what he's talking about.
It's easy to do that by editing the /etc/fstab file.

I also like to set swappiness to 10 in my /etc/sysctl.conf file so the operating system will prefer to use RAM but will use the swap file or swap area if it needs to. Performance tuning with 'swappiness' - Ubuntu Community Docs.


I like to add the boot option 'elevator=noop' to my grub.cfg too, Noop scheduler - wikipedia.

I use these settings to get the best performance from my SSD or flash drive. So far I have not noticed any problems with flash memory wearing out.

Let me know if you want more details on anything, I'll elaborate if you're interested.

[gabrielcik]

How can i use this option (elevator=noop) in Karmic?
I know it uses grub2 and so there is not more menu.lst...

Thank you

[psusi]

Hello,

I want to use the ext4 since i had problems with ext2.

I have a sdd and i heard it would be better to remove the journaling...

I found on the net this command for to remove it:
sudo tune2fs -O ^has_journal /dev/sdXN

is it safe? or maybe it is better to leave it on?

Thank you

Turning off journaling is not a good idea since it leaves your filesystem vulnerable to corruption if you crash.

You need to have the filesystem checked periodically, and especially after you lose power. It is not a bad thing that ext2 requires a filesystem check after a hard power-off. ext3 and ext4 also require a fsck after hard power-off.

No, you don't; that's the whole point of journaling. As long as you have the journal, you DON'T need a fsck after a crash, or ever really, unless you think something went horribly wrong and corrupted your filesystem.

According to the following link we probably don't need to worry about it too much because if we're using an OCZ SSD with an indilinx controller it's already taken care of. The indilinx controller will do the job by itself without waiting to be told, Indilinx firmware cleans dirty SSDs, restores performance while idle.
We would need to check if we have the right firmware update for that to work.

That's exactly what the TRIM command is for; to tell the drive what blocks are free so that it CAN clean them. This article seems to be misleading in that it suggests that their firmware does it by magic rather than with TRIM.