Ext2 as a root filesystem: any contraindication?

[Ottavio Caruso]

Hello,

I am going to move my 6.1.2 amd64 installation from a USB drive to a
partition in my hard drive. What if I use ext2 as a root filesystem?

Any contraindications? I know already I'm not going to have
journalling, but I can live with it.

The only reason would be that it would make it easier for me to resize
the partition (as in MBR partition, not slice) later on with Gparted.

Unless somebody can suggest a realtively way to resize a ffs/ffs2 partition.

Thanks

[Greg Troxel]

Post by Ottavio Caruso
I am going to move my 6.1.2 amd64 installation from a USB drive to a
partition in my hard drive. What if I use ext2 as a root filesystem?
Any contraindications? I know already I'm not going to have
journalling, but I can live with it.
The only reason would be that it would make it easier for me to resize
the partition (as in MBR partition, not slice) later on with Gparted.
Unless somebody can suggest a realtively way to resize a ffs/ffs2 partition.

man resize_ffs :-)

Also, get an external disk, which you need for backup anyway, and dump,
adjust, newfs, and restore.

People at BBN tried to use ext2 as root on evbppc, and we ran into
trouble. So I expect that you are going to have some issues, and will
be better off with ffs (where you can use wapbl, but really because it
will be reliable).

[Ottavio Caruso]

Post by Greg Troxel

Post by Ottavio Caruso
Unless somebody can suggest a realtively way to resize a ffs/ffs2 partition.

man resize_ffs :-)

A couple of problems with that:

1) BUGS
Doesn't currently support shrinking FFSv2 file systems

Is it still so?

2)

DESCRIPTION
resize_ffs resizes a file system.

My understanding is that resize_ffs resize a partition within the bsd
slice, not the whole MBR partition. I thought that "fdisk -u" would
have done the job.

3) It's not relatively easy.

[Manuel Bouyer]

Post by Ottavio Caruso

Post by Greg Troxel

Post by Ottavio Caruso
Unless somebody can suggest a realtively way to resize a ffs/ffs2 partition.

man resize_ffs :-)

1) BUGS
Doesn't currently support shrinking FFSv2 file systems
Is it still so?
2)
DESCRIPTION
resize_ffs resizes a file system.
My understanding is that resize_ffs resize a partition within the bsd
slice, not the whole MBR partition. I thought that "fdisk -u" would
have done the job.

It resizes a filesystem, not a partition. That's different things.
To change the partition's size you use disklabel and/or fdisk

[Niels Dettenbach]

Post by Ottavio Caruso
Any contraindications? I know already I'm not going to have
journalling, but I can live with it.

...hmmm,
if NetBSD is able to boot from ext2 (not tested yet) it could make performance
differences - but this may depend from the storage media too. I#m not shure
how far the ext2 driver in NetBSD is comparable in optimizations to linux or
the "native" NetBSD filesystem drivers.

But if i read something like this:
http://wiki.netbsd.org/tutorials/how_to_share_an_ext2_partition_with_linux/

i assume that you could run into further limitations if you are limited to the
oldest ext2 revision (i.e. if you have to handle larger directory indexes or
large files).

If "resizing" is the only reason for your to choose ext2 i would look for
other options / solutions with i.e. resize_fss or the ported growfs.

hth a little

cheerioh,

Niels.

[Lars-Johan Liman]

[Reading some old mail ...]

Post by Ottavio Caruso
What if I use ext2 as a root filesystem?

This can be done. We did it as an experiment with NetBSD under Xen.

The one thing that we ran into was that /dev/ was mounted as a union
file system on top of an FFS system. That works fine for FFS, but the
ext2 driver doesn't support union mounts, so you might have to manually
populate the /dev directory in the undelying ext2 file system by using
/dev/MAKEDEV in single user mode; and then avoid the union mount. After
that it ran like a charm.

The error mode was that "/dev/console" seemed to be missing, which
created all kinds of surprises for the OS. (It's all _very_ confusing
until you pinpoint the problem. ;-)

Best regards,
/Lars-Johan Liman

(who realizes he should change his
address on the list after the company
merger ;-)
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