On Mon, Aug 17, 2009 at 09:07:26AM -0400, Theodore Tso wrote: > On Tue, Aug 04, 2009 at 02:15:07AM +0300, Jari Aalto wrote: > > However in article: > > > > "Barriers and journaling filesystems" 2008-05-21 > > http://lwn.net/Articles/283161/ > > > > ... ext3 and ext4 filesystems, by default, do not use barriers. The > > option is there, but, unless the administrator has explicitly > > requested the use of barriers, these filesystems operate without > > them - though some distributions (notably SUSE) change that default. > > ... > > Ext4 enables barriers by default; this is documented in the kernel > Documentation tree, in Documentation/filesystems/ext4.txt. Good point, I have added info about the default ext{3,4} behavior to mount.8. Karel >From d5ea216bf6a5f294984b56da51fc3e09e822247d Mon Sep 17 00:00:00 2001 From: Karel Zak <kzak@xxxxxxxxxx> Date: Mon, 17 Aug 2009 15:35:13 +0200 Subject: [PATCH] mount: add info about ext{3,4} barriers to mount.8 Signed-off-by: Karel Zak <kzak@xxxxxxxxxx> --- mount/mount.8 | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) diff --git a/mount/mount.8 b/mount/mount.8 index 3d45100..f4ef7e8 100644 --- a/mount/mount.8 +++ b/mount/mount.8 @@ -1246,6 +1246,10 @@ internal file system integrity, however it can allow old data to appear in files after a crash and journal recovery. .RE .TP +.BR barrier=0 " / " barrier=1 " +This enables/disables barriers. barrier=0 disables it, barrier=1 enables it. +The ext3 does not enable write barriers by default. +.TP .BI commit= nrsec Sync all data and metadata every .I nrsec @@ -1296,6 +1300,8 @@ penalty. If your disks are battery-backed in one way or another, disabling barriers may safely improve performance. The mount options "barrier" and "nobarrier" can also be used to enable or disable barriers, for consistency with other ext4 mount options. + +The ext4 enables write barriers by default. .TP .BI inode_readahead= n This tuning parameter controls the maximum number of inode table blocks that -- 1.6.2.5 -- To unsubscribe from this list: send the line "unsubscribe util-linux-ng" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
