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HEADS UP NetBSD lvm support

Hi folks,

Today I have committed couple of changes to haad-dm branch. With these
latest changes I was able to use lvremove, lvextend, lvreduce etc..

I believe that haad-dm is currently in a good shape and it only needs
more testing to fix all possible outstanding bugs. for all brave testers
I have created new chapter in NetBSD Guide about lvm support [1].

Instructions how to test lvm:

1) update src/sys and src/external to haad-dm branch.
2) if you kernel supports new modules build new module in src/sys/ modules/dm or build new kernel with this line pseudo-device dm line. Load module/ reboot new kernel.

3) build lvm2tools and libdevmapper in src/external/gpl2/ and install them.

4) use tools lvm to manage your lvm devices.

   lvm pvcreate /dev/raw_disk_device # create Physical Volume *

lvm vgcreate vg00 /dev/raw_disk_device #create Volume Group-> pool of available disk space.

lvm lvcreate -L20M -n lv1 vg00 # create Logical volume aka Logical disk device

newfs -F -s 20M /dev/vg00/rlv1 # newfs without -F and -s doesn't work

   mount /dev/vg00/lv1 /mnt # Enjoy

After reboot you can activate all existing LV in system with command.

   lvm vgchange -a y

   You can use

lvm lvdisplay vgdisplay pvdisplay to see at status of your LVM devices.

   You can also use lvm lvextend/lvreduce to change size of LV.

I haven't tested my driver on SMP system there are probably some bugs in locking so be aware of it :) and do not try to extend/reduce partition during IO
   (something bad can happend).


1) review locking I will probably allow only one ioctl call to be inside dm driver
      at time.

   2) Write snapshot driver only skeleton was written yet.

3) Add ioctls needed to correct newfs functionality. I tried to implement them
      in device-mapper.c::dmgetdisklabel but it doesn't work still.

4) Write lvm rc.d script to enable LVM before disk mount so we can use lvm for
      system partitions.

* If you are using disklabel partition a as raw_disk_device it MUST start after disklabel
  blocks. Offset of a partition should be 65s.

P.S. I will not be able to answer any bug mails till sunday.




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