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mount: update mount.8 about barrier mount options defaults 

This patch comes originally from Jan Kara <jack@suse.cz> 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
This commit is contained in:
Ruediger Meier 2014-03-21 12:31:39 +01:00
parent 412791a995
commit 94b559e08e
1 changed files with 16 additions and 21 deletions
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37
sys-utils/mount.8
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@ -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.