[ale] Ext4 adoption anyone?

James Sumners james.sumners at gmail.com
Wed Jan 21 17:33:26 EST 2009


2009/1/21 Michael B. Trausch <mike at trausch.us>:
> On Wed, 21 Jan 2009 15:21:02 -0500
> James Sumners <james.sumners at gmail.com> wrote:
>
>> You might give [1] a read to see if the new features benefit your
>> situation. I like the sound of improved performance, but I'm not sure
>> if I would be willing to trade mounting and Ext3 partition as Ext2.
>> That one feature is very handy if/when the need arises. It sounds to
>> me like a pure Ext4 (created from scratch) filesystem cannot be
>> mounted as a previous version.
>
> The feature that blocks usage is extents.  You can convert back from
> ext4 to ext3 simply by remounting the filesystem with extents disabled
> and making a copy of any files that use extents, and then removing the
> files that have extents and disabling that feature on the filesystem.
>
> That said, I don't know that I'd need to do such a thing.  I suppose
> this is probably because I tend to use custom kernels.  :-)  Even in
> 2.6.27 (the kernel that Ubuntu Intrepid uses) you can mount an ext4
> filesystem as ext4dev, if you enable the flag on the filesystem that
> says that it's okay for testing code to mount it.  I haven't had a
> problem doing that on 2.6.27 as shipped and updated on Intrepid, but
> it's been a little while since I've booted that kernel.

Custom kernels have nothing to do with having to recover from a crash.
In the early days of Ext3, I had a couple instances where I had to
mount my Ext3 partition as Ext2 to recover data from it. This is
really only necessary when the Ext3 journal gets corrupted.

The method you describe for mounting Ext4 as Ext3 sounds like a lot of work.

> I traditionally use a very small ext2 partition for booting... I've
> never seen the need for /boot to have a journal or any other special
> features, since it's only ever updated when a new kernel is installed.
> I usually mount /boot with the sync mount option, as well; not that big
> a bother since the filesystem is only really used by the boot loader
> and various utilities that are only run when updating the kernel.  Just
> my two cents...

I don't usually create a separate /boot partition. In fact, I rarely
create any separate partitions except for /home. I just haven't seen a
need for doing so on a "desktop" machine. Creating a separate /home
just makes it easier to change distributions or wipe the current load
and start over.



-- 
James Sumners
http://james.roomfullofmirrors.com/

"All governments suffer a recurring problem: Power attracts
pathological personalities. It is not that power corrupts but that it
is magnetic to the corruptible. Such people have a tendency to become
drunk on violence, a condition to which they are quickly addicted."

Missionaria Protectiva, Text QIV (decto)
CH:D 59


More information about the Ale mailing list