[HEADS-UP] NetBSD LVM support

[Adam Hamsik <haaaad%gmail.com@localhost>]

Hi folks,

I would like to give you small christmas gift ;). I want to announce,  
to people who
do not follow source-changes closely that from yesterday NetBSD has a  
Logical Volume
Manager functionality in base system(For those who ask wtf? is the LVM  
it is
simple system used to create/resize/delete virtual partitions from in  
system storage
space[1], [2]).

HOWTO get NetBSD with LVM

You need to build system from sources with flag MKLVM set to yes.

e.g.
$cd /usr/src
$./build.sh -u -U -V MKLVM=yes distribution

After successful build create sets and update system with them. You  
can also run make
install (as root) in src/external/gpl2/lvm2 to install userland part  
of LVM into
the existing NetBSD system. There is also simple driver used by LVM2  
tools in our kernel
in src/sys/modules/dm you have to install and load this driver before  
you test lvm.
The NetBSD LVM uses same tools as Linux and therefore we have the same  
user interface as
is used in many common linux distributions. [3], [4]

LVM use cases:
In server with more than one disk you can create one big Volume group  
from one or more disks
and create used partitions on it. If you later find out that choosen  
size of Logical Partition
is too small for your usage you can resize it with lvresize  
command(You can also resize
Volume Group with vgresize).

On XEN server you can create Logical partition for ever system and you  
don't need to used files/vnds
anymore. LV's can be easily resized, so you don't need to add new  
disks to domU when machine fills
it disk.

TODO tasks:

Currently I haven't integrated LVM with our sysinst, it is not  
possible to use Logical Volume for /
partition, but other partitions as /usr /var should be ok if you use  
this [5]rc.d script to start Volumes
before mounting. We don't have snapshot support for logical volumes (I  
want to look at it soon). Add
new targets.

[1]http://en.wikipedia.org/wiki/Logical_Volume_Manager_(Linux)
[2]http://en.wikipedia.org/wiki/Logical_volume_management
[3]http://tldp.org/HOWTO/LVM-HOWTO/
[4]http://www.redhat.com/docs/manuals/csgfs/browse/4.6/Cluster_Logical_Volume_Manager/index.html
[5]www.netbsd.org/~haad/lvm
Regards

Adam.