I'm currently using mandriva 2007 with an ext3 hard disk and for sure I want to upgrade to an new kernel 2.6.20 when it comes out. I've heard that it should support ext4 which wasn't possible before. Therefore I'm wondering how I should get that filesystem used, I will have to reformat the whole harddisk, am I right? But isn't this some kind of a hen-egg problem, because if I will install linux on the ext4 formatted hard-disk anew, per default it will have an older kernel than 2.6.20. So it doesn't support the hard-disk filesystem and I can't compile the new kernel??

And currently there is a 2.6.20.rc2 kernel out. I'm considering installing that one because right now, I have free time up to New Years Day (The stable kernel won't (likely) come out untill then, there have been aprod. 5 releases before the stable ones in the past ). Will that cause any major problems, just installing the prerelease and the real kernel just afterwards with less system crashs?

Of course these are difficult questions but I have little experience with these matters, but need important features of the new kernel like ext4 and the virtual machine support.
Thanks in advance!

If you want to install linux on a new filesystem, install linux twice on two separate partitions. Both should have a kernel capable of mounting the new filesystem. Boot into one of them and mount the other partition somewhere (eg, /mnt/other) then tar up the whole partition
cd /mnt
tar cjfp other.tar.bz2 other
Then unmount the partition
umount /dev/whatever
Format the partition
mkfs.whatever /dev/whatever
Edit /etc/fstab to reflect the new filesystem then mount it again
mount -a
then untar everything onto the now empty partition
tar xf other.tar.bz2
Edit the /mnt/other/etc/fstab on the other system to reflect the new filesystem on its root partition.
Of course, this is all very dangerous so Beware! Here be monsters! Turn back! Don't do it! etc

Thanks for your reply


As I'm new to linux I was a bit badly informed about the filesystems, hence I'll give a little summary. Experienced users may tend to switch off here ;-)
Edit: So I'll wait a bit for turning to ext4.

I read about the filesystems ext4 and Reiser4. Even though they have the same version number ;-) they are completely different, so ext4 is not an abbreviation for Reiser. Reiser4 won't be included in the new 2.6.20 kernel, ext4 will. For an upgrade Reiser3-> Reiser4 you'll have to format your disk, for ext3->ext4 not. You can just switch from ext3 to ext4. But notice, that at the moment ext4 is still experiementally. The difference ext3 to ext4 is (amongst other features) the support of even "§%& bigger harddisks and some extents option which prevents that the harddisk gets fragmented.