[linux-lvm] LVM Partition Dependency

Heinz J. Mauelshagen Heinz.Mauelshagen at t-online.de
Mon Oct 30 18:37:01 UTC 2000

Hi Paul.

On Mon, Oct 30, 2000 at 10:01:09AM -0600, pbmonday at imation.com wrote:
> I'm trying to construct an LVM solution with block devices that are not
> located in the partition table (becuase they are not a local fixed physical
> disk). 

Sounds like NBD or friends.

> I'm curious how deep the dependency on being in the partition goes
> with the LVM.

Actually not very deep.

> For example, I know the /proc/partitions file is checked during
> pvcreate...

It is done in tools/lib/lvm_dir_cache.c
You need to extend the devdir array.

> if I rewrote pvcreate to get around this check would I encounter
> other dependencies on actually being a drive partition located on the local
> machine later?

It is less a question of beeing local to the machine because there's NBD
support build in anyway. It's more a question of checking for supported
devices in tools/lib/lvm_check_dev.c based on device majors.

> Or, if I added my block device to the partitions table, would that be
> enough to fulfill all requirements of being a local partition that are
> required by the LVM?

That and addiing a new device major to lvm_check_dev.c should do it.

> Would the problems be only with the user space tools, or would there also
> be problems in the kernel module?

The driver only remaps devices and sectors based on tables the userspace
supplies. The only thing it needs to care about that it is a block device ;-)

> Just curious on how far I would have to go to "trick" or "modify" the LVM
> to accept something other than a local hard drive partition.

As i mentioned above: NBD should work.

> Thank you,
> Paul Monday
> pbmonday at imation.com


Heinz      -- The LVM guy --


Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Bartningstr. 12
                                                  64289 Darmstadt
Mauelshagen at Sistina.com                           +49 6151 7103 86
                                                       FAX 7103 96

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