ext3 on OldWorld Macs

[Richard Petty]

Yes, I did convert two of my three partitions to ext3 by hand, but 
there's reason why I didn't convert the partition to which YDL boots.


This first citation below is from Red Hat:

http://www.redhat.com/support/wpapers/redhat/ext3/index.html
If you are transitioning your root file system, you will
have to use an initrd to boot. Run the //mkin//itrd// program as
described in the manual and make sure that your LILO or
GRUB configuration loads the initrd. (If you fail to make
that change, the system will still boot, but the root file
system will be mounted as ext2 instead of ext3 ? you can
tell this by looking at the output of the command *cat
/proc/mounts*.)



This second citation is the one that really got my attention:

http://www.zipworld.com.au/~akpm/linux/ext3/ext3-usage.html
Non-LILO bootloaders The LILO bootloader doesn't know
about filesystems - it uses a pre-prepared list of blocks
to locate and load the operating system image into memory.
However other (smarter?) software such as SILO 
<http://silo.sourceforge.net/> (SPARC) and
yaboot <http://penguinppc.org/projects/yaboot/> (built on Open Firmware) 
(PPC) have filesystem
drivers in them, and they know how to directly open and
load an ext2 file. This can be a problem if the boot file-
system is ext3, and it has suffered an unclean shutdown.
When ext3 is in this state it is not compatible with ext2
-- it needs recovery to be performed. This incompatibility
is recorded in the filesystem's superblock, and a fully
ext2-compatible bootloader implementation /should/ complain
and refuse to open files on the filesystem. This is, of
course, not what we want to happen. The system won't boot!

Versions of yaboot prior to 1.3.5 will refuse to boot from
a "needs recovery" filesystem. Version 1.3.5 and later
support ext3 via libext2fs <http://e2fsprogs.sourceforge.net/> .

SILO also has the correct compatibility checks, and boot-
ing from a "needs recovery" ext3 filesystem will cause
SILO to complain about "too many symlinks", or something
else inappropriate. To avoid this serious problem you
will need to ensure that your boot filesystem is of type
ext2, not ext3 (or patch SILO to defeat the compatibility
checks?)


I need assurance that even if the boot partition does not go down 
cleanly that I'll be able to boot to it. This documentation implies that 
I won't be able to because, not only do I not have a recent enough 
version of yaboot, I don't use yaboot at all on my Old World Mac.

Terra Soft Systems doesn't seem to think I should run ext3, either, and 
there's evidence that supports their position. Therefore, I'm hesitant.

--Richard


Cesar Cardoso wrote:

> You wrote on YDL list:
>
>> I want to run ext3 on it and have a few questions... Firstly (and
>> predictably), the ext3 conversion tool included on the YDL 2.2 disk
>> won't do it's job on Old World systems and any New World machine not
>> running yaboot > whatever.
>
>
> Do the conversion by hand:
>
> # tune2fs -j /dev/hdax
>
> change the mount point of /dev/hdax to ext3 on /etc/fstab
>
> reboot
>
> It's what the script does (it's a Python script, so you can read it :-).
> It's what I did on my PowerMac 5500/250.