Comments on: Mount options to improve ext4 file system performance

By: everge48

everge48 — Mon, 21 Nov 2011 11:08:11 +0000

^ Yes it is redundant.

By: LohPhat

LohPhat — Sat, 10 Sep 2011 19:40:38 +0000

1. What is the default journal mode if the “journal_data” | “journal_data_ordered” | “journal_data_writeback” are not specified? Is it distro specific? If so, how do I find out?

Is the /etc/fstab mount option “data=writeback” redundant if “journal_data_writeback” is set in the superblock?

By: Install MySQL on SSD, best mount options? - Admins Goodies

Install MySQL on SSD, best mount options? - Admins Goodies — Tue, 09 Aug 2011 23:20:42 +0000

[...] This blog provides several speed-optimizing mount options you might consider, and explains some of the risks of using some of them. http://blog.smartlogicsolutions.com/2009/06/04/mount-options-to-improve-ext4-file-system-performance... [...]

By: Improve File-Systems Performance « XT Zone

Improve File-Systems Performance « XT Zone — Fri, 22 Jul 2011 05:55:34 +0000

[...] options offer an easy way to improve speed without reformatting. Some articles boosted rails test suite running time by around 30% by adding certain mount options for their ext4 [...]

By: Michael T. Babcock

Michael T. Babcock — Fri, 08 Jul 2011 19:44:04 +0000

This discussion is one of the reasons I partition my drives with more than one simple root partition; different file system parameters suit different types of data.

For example, if you use two, a root and a /home filesystem, you can set your /root to be full journaled writes with noatime for fast reads but slow writes and almost no possibility of data corruption where your binaries live. Then your /home you can play a bit more fast and loose with if you like.

By: Joshua Dickerson

Joshua Dickerson — Fri, 06 May 2011 16:18:53 +0000

Instead of rebooting, just use “mount -a”

By: Nick Gauthier

Nick Gauthier — Sat, 18 Dec 2010 02:02:14 +0000

Cool, thanks James. Slightly more dangerous, but probably even better for performance.

By: James

James — Sat, 18 Dec 2010 01:32:42 +0000

EXT4 also can be created without a journal. Full journaling on EXT4 turns off delayed allocation as does the mount option ‘nodelalloc’ with ordered mode makes it behave like EXT3.

http://kernelnewbies.org/Ext4

By: Admin: Linux file server performance boost (ext4 version) | Cypris' lookout

Admin: Linux file server performance boost (ext4 version) | Cypris' lookout — Sun, 03 Oct 2010 04:34:40 +0000

[...] Mount options to improve ext4 file system performance [...]

By: Grogan

Grogan — Tue, 21 Sep 2010 23:04:25 +0000

Andrius says: “I’m not completely sure, but it seems data=writeback and journal_data_writeback is not the same.”

Yes, it is. It is simply setting the default journal option in the superblock. The reason for that first step with tune2fs is in case that is your root filesystem. You cannot remount a filesystem and change the journal mode, it has to be completely dismounted first.

In just about every distro (boot loader option) your filesystem will already be mounted read-only before fstab options come into play, and trying to change the journal mode will result in mount refusing to remount the filesystem, it will stay in read-only mode and your system will not boot properly. (you’ll be lucky to get a shell depending on distro and certainly, if you’re doing this remotely, you’d be buggered)

“journal_data_writeback is option, when full journaling is enabled with data=journal. data=journal is the slowest and safest mode. As you said journal_data_writeback keep a journal and gives best performance in data=journal mode.”

No, they are mutually exclusive. data=journal would override the journal_data_writeback setting in the superblock at mount time.

You’re correct about the pseudo journaling though (metadata only, whether ordered or writeback modes). The only journal option that gives you real journaling is data=journal

———————————

Nick, thanks for the blog post. I came across it while looking for mount options to improve ext4 performance. What I think is that you have to do backups anyway, so it’s better to use options that favour performance than data safety at the expense of performance. At least on my own workstations, anyway.