disable journaling on ext3
 

We are going to run a couple of tests for a database. One of these tests are going to be to test database performance under heavy loads on ext3 with journaling, ext3 without journaling and then of course using raw devices.

I've tried searching for disabling journaling on ext3 (not ext2), but to no avail. The Sybase press releases shows that there are differences in performance with, so I know there is a way to disable it.

How can I disable journaling on ext3 without having to revert to ext2? Would I need to drop the partition and recreate it or is there a simpler way?

Sorry, I'm quite new to linux in general, so detailed instructions are preferred. We are doing the tests on SUSE 9 SLES and RH 3 AS

TIA

To the best of my knowledge (meaning that you should take this with a rather large grain of salt) you cannot separate ext3 from journaling. To say it another way, "ext2 + journaling = ext3" or alternatively "ext3 - journaling = ext2" so if you simultaneously do not want to use either ext 2 or journaling, then I don't know what you'd do other than to switch to a completely different file system.

Perhaps other more knowledgable people will post their comments, but I'm not aware of a "disable journaling" option within ext3. Again, I am not the guru on this topic and would defer to people with better info. -- J.W.

Thats what I think as well, but the Sybase technical docs has got a benchmark one ext3 "with and without journaling", so thats why I think its actually possible. Maybe you have to set the journal to 0 bytes, or something silly like that (I have no clue where to start looking on how to do this).

There are some other changes, afaik, made to ext2 to get to ext3 as well. Read somewhere that ext2 writes to disk every 30 seconds and ext3 every 5, so that can make a big difference in i/o performance on a database (not sure if this is true though... sounds a bit fishy to me).

Would you by any chance be able to ask Sybase how they disabled journaling with ext3 to run the benchmark tests?

Unfortunately, not. They dont have email support on their website, only postal and telephonic. Since I'm not from the states, I'm not going to make a phone call at 1 in the morning so that I can catch them awake :)

You can speed up journal filesystem by placing the journal on another seperate drive, so the computer can write data and journal in parallel instead of one at a time. You can try other filesystems like JFS or XFS. JFS does not defrag but it is fast at writing and reading files. XFS is much faster than JFS and it defrags but it does not write to the disk unless it needs too. XFS advantage is it works all the time in memory so applications like database, file server, web can be access very, very fast.

You have to experiment what filesystem and its settings will work better for your application.

Thanks. Glad to know its possible, but how can you completely disable journaling? i.e have ext3 with no journal without having to revert to ext2?

Like J.W. said there is no way you can disable journal feature of ext3 because it will work like ext2.

ext2 + journal = ext3
ext3 - journal = ext2

ext3 is a hybrid fileystem because it works both ways even if the journal is corrupted. Though without journal it becomes ext2.

Like I said eariler, you have to experiment with different formatting options and filesystems to get the performance that you want. Benchmarks are estimates, so do not compare their results to your setup because they are different.

For database environments, you can increase performance if you use large cache for either the controller or database service. To really speed up performance, use a solid state hard drives. They are about 100 times faster than SCSI hard drives.

Why not just mount the drive as ext2?

As someone said, that is the advantage to ext2.

If your databas stuff is on the same drive as you are booting from just modify your fstab file and reboot. If it is on a seperate drive... it becomes much easier.

I looked at the remount option, but I'm not sure if you can remount as a different file system.

Disabling ext3 journaling consists of converting to ext2: it's that simple. Here is a short, sweet tutorial on how to do it.

ext3 != ext2 + journaling
 

Maybe back in 2003/2004 this was true, but ext3 and ext2 do not behave the same, ext2 tends to be much slower for metadata updates, and sync more often. ext3 is actually faster than ext2 in some workloads, and turning off ext3's journal should make it faster, but using ext2 as a 'ext3-journaling' will not do that.

The closest you can get to disabling ext3 journaling I have found is to use a separate ram disk as a journaling device, this way writes to the journal are so fast they will come close to being an ext3 with no journal, however this is not the same as ext3-journal, but close enough.

mke2fs journal_dev -O /dev/ram0
mke2fs -J size=8,device=/dev/ram0 /dev/sde1
mount /dev/sde1 /media/ext3nojournal

You just bumped a six year old thread.

I believe if the original poster has not found an answer by now he probably won't even with your assistance.