Novell LINUX ENTERPRISE SERVER 10 - INSTALLATION AND ADMINISTRATION 11-05-2007, Руководство по установке

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Ext3 in the
data=journal
mode offers maximum security (data integrity), but
can slow down the system because both metadata and data are journaled. A rela-
tively new approach is to use the
data=ordered
mode, which ensures both data
and metadata integrity, but uses journaling only for metadata. The file system
driver collects all data blocks that correspond to one metadata update. These data
blocks are written to disk before the metadata is updated. As a result, consistency
is achieved for metadata and data without sacrificing performance. A third option
to use is
data=writeback
, which allows data to be written into the main file
system after its metadata has been committed to the journal. This option is often
considered the best in performance. It can, however, allow old data to reappear in
files after crash and recovery while internal file system integrity is maintained.
Unless you specify something else, Ext3 is run with the
data=ordered
default.
25.2.4 Converting an Ext2 File System into
Ext3
To convert an Ext2 file system to Ext3, proceed as follows:
1 Create an Ext3 journal by running
tune2fs -j
as
root
. This creates an Ext3
journal with the default parameters.
To decide yourself how large the journal should be and on which device it should
reside, run
tune2fs -J
instead together with the desired journal options
size=
and
device=
. More information about the tune2fs program is available
in the tune2fs manual page.
2 To ensure that the Ext3 file system is recognized as such, edit the file
/etc/
fstab
as
root
, changing the file system type specified for the corresponding
partition from
ext2
to
ext3
. The change takes effect after the next reboot.
3
To boot a root file system set up as an Ext3 partition, include the modules
ext3
and
jbd
in the
initrd
. To do this, edit
/etc/sysconfig/kernel
as
root
, adding
ext3
and
jbd
to the
INITRD_MODULES
variable. After saving
the changes, run the
mkinitrd
command. This builds a new initrd and prepares
it for use.
File Systems in Linux 473