[linux-lvm] Why vgscan not in kernel?

josv at osp.nl josv at osp.nl
Mon Jun 25 12:54:52 UTC 2001

If the VG scan process is in the kernel, that means that it
will *always* be executed (unless there is a kernel command
line option to disable it).

The issue then is that the VGSCAN in the kernel should be
*completely* resistant against every possible data corruption
and should be able to recover from it gracefully. This is not
as easy as it looks.

With VG scan in a separate executable, it is easier to prevent
it from executing...


And thus it came to pass that Dirk Heinrichs wrote:
(on Mon, Jun 25, 2001 at 02:52:00PM +0200 to be exact)

> Steven Lembark wrote:
> > 
> > >> upon boot, SCSI and IDE drivers check harddrives attached to the device
> > >> for partitions. Wouldn't it be better to have similar functionality
> > >> (scanning for VG's) for LVM in the kernel, instead of using a userland
> > >> command?
> > 
> > It is rather dangerous unless you have a separate kernel w/o LVM or
> > a boot option (e.g., -lm) that allows booting with LVM turned off.
> > Otherwise you can easily end up unable to reboot with a corrupt LVM
> > system.
> I don't get the point here. Why is it dangerous to move the VG scan from
> vgscan into the kernel module? Why should this corrupt LVM? Can you
> explain this in more detail?
> Bye...
> 	Dirk
> -- 
> Dirk Heinrichs		| Tel:	+49 (0)241 413 260
> Configuration Manager	| Fax:	+49 (0)241 413 2640
> QIS Systemhaus GmbH	| Mail:	dheinrichs at qis-systemhaus.de
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With all the things you are losing,
You might as well resign yourself,
And try and make a change...

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