The ext3 file system is a version of the ext2 file system which
has been enhanced with journaling. It supports the same options
as ext2 as well as the following additions:
journal_dev=devnum/journal_path=path
When the external journal device's major/minor numbers
have changed, these options allow the user to specify the
new journal location. The journal device is identified
either through its new major/minor numbers encoded in
devnum, or via a path to the device.
norecovery/noload
Don't load the journal on mounting. Note that if the file
system was not unmounted cleanly, skipping the journal
replay will lead to the file system containing
inconsistencies that can lead to any number of problems.
data={journal|ordered|writeback}
Specifies the journaling mode for file data. Metadata is
always journaled. To use modes other than ordered on the
root file system, pass the mode to the kernel as boot
parameter, e.g. rootflags=data=journal.
journal
All data is committed into the journal prior to
being written into the main file system.
ordered
This is the default mode. All data is forced
directly out to the main file system prior to its
metadata being committed to the journal.
writeback
Data ordering is not preserved – data may be
written into the main file system after its
metadata has been committed to the journal. This
is rumoured to be the highest-throughput option.
It guarantees internal file system integrity,
however it can allow old data to appear in files
after a crash and journal recovery.
data_err=ignore
Just print an error message if an error occurs in a file
data buffer in ordered mode.
data_err=abort
Abort the journal if an error occurs in a file data buffer
in ordered mode.
barrier=0 / barrier=1
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.
commit=nrsec
Start a journal commit every nrsec seconds. The default
value is 5 seconds. Zero means default.
user_xattr
Enable Extended User Attributes. See the attr(5) manual
page.
jqfmt={vfsold|vfsv0|vfsv1}
Apart from the old quota system (as in ext2, jqfmt=vfsold
aka version 1 quota) ext3 also supports journaled quotas
(version 2 quota). jqfmt=vfsv0 or jqfmt=vfsv1 enables
journaled quotas. Journaled quotas have the advantage that
even after a crash no quota check is required. When the
quota file system feature is enabled, journaled quotas are
used automatically, and this mount option is ignored.
usrjquota=aquota.user|grpjquota=aquota.group
For journaled quotas (jqfmt=vfsv0 or jqfmt=vfsv1), the
mount options usrjquota=aquota.user and
grpjquota=aquota.group are required to tell the quota
system which quota database files to use. When the quota
file system feature is enabled, journaled quotas are used
automatically, and this mount option is ignored.
