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5. Get, Set, Go...
$ cp ext3-2.4-0.x.y.patch.gz /usr/src
$ gunzip ext3-2.4-0.x.y.patch.gz
$ patch -p0 < ext3-2.4-0.x.y.patch
$ cd /usr/src/linux
$ make mrproper
$ make menuconfig
Under the filesystems menu, select ext3.
Please also select "JBD debugging support", as it will produce useful
diagnostics if something goes wrong.
The filesystem may be compiled into the kernel or built as a module.
Building it into the kernel can simplify the gathering of diagnostic
information if something fails.
WARNING : If u are converting your existing ext2 root file system to
ext3 than compile ext3 support in the kernel since u will
need it on startup :-)
Debian Users :
------------
Once the above make menuconfig step is over, just type
make-kpkg --revision=ext31.0 kernel-image
to start compilation of the kernel. This will create a deb
file in /usr/src with your customised kernel with ext3 support.
Just type dpkg -i kernel-image* to install the new kernel :-)
Edit your LILO (/etc/lilo.conf) or GRUB (/boot/grub/menu.lst)
configuration file to reflect the new kernel. Update the MBR by
giving the appropriate command for your boot loader.
( lilo -v for LILO )
Redhat Users :
------------
Redhat users are not so lucky as Debian users. You guys will
have to type the following commands to compile and install the
kernel:
$ make dep
$ make clean
$ make bzImage
$ make install
$ make modules
$ make modules_install
Edit your LILO (/etc/lilo.conf) or GRUB (/boot/grub/menu.lst)
configuration file to reflect the new kernel. Update the MBR by
giving the appropriate command for your boot loader.
( lilo -v for LILO )
Voila !!! A major headache over .......... Hush.............
An ext2 filesystem maybe converted to ext3 by creating a journal file
on it. To do this, run
tune2fs -j /dev/hdXX
on the target filesystem. The filesystem is now ext3!
Note that the filesystem need not be unmounted for this operation.
Simply run
mke2fs -j /dev/hdXX
to create a new ext3 filesystem on that device.
A feature of e2fsck is that it will regularly force a check of a
filesystem even if the filesystem is marked clean. Typically, this
happens on every twentieth mount or every 180 days, whichever comes
first.
This still happens with ext3, and is quite possibly not what you want
to happen - one of the reasons you chose ext3 was to avoid the downtime
which is caused by a long fsck.
So it is a good idea to turn this feature off for ext3.
Use the command
tune2fs -i 0 /dev/hdxx
To disable the checking.
This is very important. Just change ext2 to ext3 in /etc/fstab
For ex. :
/dev/hda3 / ext2 defaults,errors=remount-ro 0 1
change this to
/dev/hda3 / ext3 defaults,errors=remount-ro 0 1
Since an ext3 filesystem will not normally be checked at boot time, one
option for long-running systems is to use the LVM snapshot feature to create
a read-only snapshot of a filesystem and run a read-only e2fsck on the
snapshot to ensure that your filesystem has not been corrupted by bad RAM,
cables, disk drive, or kernel.
You need to have your filesystem on an LVM Logical Volume, and you need the
"LVM VFS Enhancement" patch applied for this to work properly (although it
may work without the VFS enhancement patch on non-busy filesystems).
For example, to run such a check on a Logical Volume (can be done at any
time while the system is running, even from a cron script). This assumes
that you will not change more than 64MB of data in a single Logical Volume
during the course of the e2fsck, and that you have this much space free in
each volume group you want to test):
# simple but stupid LV listing (hardcoded LV names to check)
#for LV in /dev/vg00/lv1 /dev/vg00/lv2 /dev/vg01/lvA /dev/vg01/lvB; do
# this assumes that all LVs have ext2/ext3 filesystems on them
for LV in `lvscan | sed -n -e '/ACTIVE/s/[^\"]*\"//' -e 's/\".*//p'`; do
SNAP=lvtempsnap
SNAPDEV=`dirname $lv`/$SNAP
lvcreate -L 80M -s -n $SNAP $LV
[ $? -ne 0 ] && echo "**** WARNING **** unable to check $LV" && continue
e2fsck -fn $SNAPDEV
[ $? -ne 0 ] && echo "**** ERROR **** problem with filesystem on $LV"
lvremove -f $SNAPDEV
[ $? -ne 0 ] && echo "**** WARNING **** unable to remove $SNAP"
done
If your root filesystem is ext3, an ext3-capable kernel will, by default,
mount it using ext3. This may be overridden via the following LILO option:
LILO: linux rootfstype=ext2
You may provide mount options to the root filesystem via LILO using the
rootflags option. For example:
LILO: linux rootflags=data=journal
The latest version of mount can automatically choose the ext3 filesystem
type. For this you should have e2fsprogs >=1.23 installed on your system
Just put 'auto' in /etc/fstab and mount will automatically recognise the
ext3 file system. Here's how it works :
1. If mount is not told the target fstype, and it detects ext3, it will
try ext3 and then ext2.
2. If mount is told fstype auto then it will detect ext3 and will try
ext3 and then ext2.
3. If fsck is told fstype auto then it will autodetect the type of the
filesystem and run the appropriate checker (which is fsck.ext2 for
both ext2 and ext3).
NOTE:
----
a) If you are using a recent Red Hat distribution and if you have built your
own util-linux from the official tarball you may have problems with mount
failing to mount filesystems. This is because Red Hat have added the "-O"
option to their version of mount. This option is used in their
/etc/rc.d/rc.sysinit, and this causes the standard mount to fail with
"unrecognised option -O".
Fix: is to edit /etc/rc.d/rc.sysinit and remove any instances of
"-O no_netdev".
b) Using filesystem type auto for the root filesystem confuses /bin/df,
and causes it to not print out information for the root filesystem.�
Fix: always specify the root filesystem as ext3 in /etc/fstab.
As of version 0.9.5, ext3 supports the placement of the journal on a
separate device. It is intended that this be a magnetic disk, or an
NVRAM device. NVRAM devices may be simulated by using Andrew Tridgell's
trivial RAM disk driver trd, which is in the ext3 CVS repository.
You will need a very recent e2fsprogs.� Version 1.23-WIP-0727 or
later.
To install trd:
mknod /dev/trd b 240 0
insmod trd.o trd_size=50000
(For a 50 megabyte device)
To create an external journal:
mke2fs -O journal_dev /dev/trd
To create an ext3 filesystem on /dev/hda5 which uses the external journal
device:
mke2fs -J device=/dev/trd /dev/hda5
mount /dev/hda5 /mnt/some/place -t ext3
NOTE :
----
a) You'll need to specify the filesystem type (-t ext3) because the
automatic filesystem type detection in mount doesn't recognise ext3
with external journals.
Of course you may use a partition on a real disk as the external journal
device - just replace /dev/trd above with /dev/hdXX.
b) Using a RAM disk driver to simulate an NVRAM device should ONLY be used for
testing. Doing so will lose the benefits of journalling at recovery time
(you will always get a full fsck of the filesystem), and in fact you will lose
data and have an increased chance of filesystem corruption after a crash.
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