From 94b559e08ee37f9597db4b64a1143e2325d949f4 Mon Sep 17 00:00:00 2001 From: Ruediger Meier Date: Fri, 21 Mar 2014 12:31:39 +0100 Subject: mount: update mount.8 about barrier mount options defaults This patch comes originally from Jan Kara and updates the default behaviour of the kernel which has been changed some years ago. See kernel docs Documentation/filesystems/ext3.txt Documentation/filesystems/ext4.txt --- sys-utils/mount.8 | 37 ++++++++++++++++--------------------- 1 file changed, 16 insertions(+), 21 deletions(-) (limited to 'sys-utils/mount.8') diff --git a/sys-utils/mount.8 b/sys-utils/mount.8 index 020943916..c2c9322f9 100644 --- a/sys-utils/mount.8 +++ b/sys-utils/mount.8 @@ -1523,12 +1523,13 @@ ordered mode. Abort the journal if an error occurs in a file data buffer in ordered mode. .TP .BR barrier=0 " / " barrier=1 " -This enables/disables barriers. barrier=0 disables it, barrier=1 enables it. -Write barriers enforce proper on-disk ordering of journal commits, making -volatile disk write caches safe to use, at some performance penalty. The ext3 -filesystem does not enable write barriers by default. Be sure to enable -barriers unless your disks are battery-backed one way or another. Otherwise -you risk filesystem corruption in case of power failure. +This disables / enables the use of write barriers in the jbd code. barrier=0 +disables, barrier=1 enables (default). This also requires an IO stack which can +support barriers, and if jbd gets an error on a barrier write, it will disable +barriers again with a warning. Write barriers enforce proper on-disk ordering +of journal commits, making volatile disk write caches safe to use, at some +performance penalty. If your disks are battery-backed in one way or another, +disabling barriers may safely improve performance. .TP .BI commit= nrsec Sync all data and metadata every @@ -1576,15 +1577,9 @@ enabled older kernels cannot mount the device. This will enable 'journal_checksum' internally. .TP .BR barrier=0 " / " barrier=1 " / " barrier " / " nobarrier -This enables/disables the use of write barriers in the jbd code. barrier=0 -disables, barrier=1 enables. This also requires an IO stack which can support -barriers, and if jbd gets an error on a barrier write, it will disable again -with a warning. Write barriers enforce proper on-disk ordering of journal -commits, making volatile disk write caches safe to use, at some performance -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. +These mount options have the same effect as in ext3. The mount options +"barrier" and "nobarrier" are added for consistency with other ext4 mount +options. The ext4 filesystem enables write barriers by default. .TP @@ -2265,13 +2260,13 @@ Enable POSIX Access Control Lists. See the manual page. .TP .BR barrier=none " / " barrier=flush " -This enables/disables the use of write barriers in the journaling code. -barrier=none disables it, barrier=flush enables it. Write barriers enforce +This disables / enables the use of write barriers in the journaling code. +barrier=none disables, barrier=flush enables (default). This also requires an +IO stack which can support barriers, and if reiserfs gets an error on a barrier +write, it will disable barriers again with a warning. Write barriers enforce proper on-disk ordering of journal commits, making volatile disk write caches -safe to use, at some performance penalty. The reiserfs filesystem does not -enable write barriers by default. Be sure to enable barriers unless your disks -are battery-backed one way or another. Otherwise you risk filesystem -corruption in case of power failure. +safe to use, at some performance penalty. If your disks are battery-backed in +one way or another, disabling barriers may safely improve performance. .SH "Mount options for romfs" None. -- cgit v1.2.3-55-g7522