LVM extends on the capabilities of MD.
- MD is limited to block devices whereas LVM is much more flexible
to support non-continguous devices as well.
- standard administration
- the LVM design could more easily extended
I would like MD to be replaced by LVM.
Resizable block devices are nice thing on it's own. For example
i am using LVM logical volumes for database files.
When offline resizing is available for ext2 we could easily make
good use of a resizable block device (enlarge ext2 fs by 100 MB
instead of dealing with partitions).
> > 2. The optional on-line LVM provides on-line resizing functionality.
> > This requires tight integration with the fs code. IMO on HP-UX
> > this requires usage of the vxfs (veritas) file system and is not
> > possible with hfs. The fsadm utility is used to perform on-line
> > operations on a file system.
>
> ... and fs resizing on Linux will need fs support too. Again, the
> question is, given that the fs needs to add support, do we need resizing
> support at the block device layer TOO? Or is that just extra
> unnecessary complexity? I for one would be quite happy with a scheme in
> which the filesystem could span multiple block devices; that would allow
> shrinking and growing at will, without any complex interaction
> requirements between the filesystem and the block device layers.
Yes. there must be some layer which maintains the available
block devices (and provides the user level tools). This should be
done in a file system independend manner.
All file systems could be used and with LVM and specifically adapted
file systems could even re-size online (at least enlarging a fs may
be possible).
Michael
-- Michael Marxmeier Marxmeier Software GmbH E-Mail: mike@msede.com Besenbruchstrasse 9 Voice : +49 202 2431440 42285 Wuppertal, Germany Fax : +49 202 2431420 http://www.msede.com/- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu