Create LVM Volume on Blockdevice

[Stefan Schörghofer]

Hi,

On Wed, 15 Jul 2015 14:49:18 +0200
Holger Parplies <wfai at parplies.de> wrote:

> Hi,
> 
> Kerim Gueney wrote on 2015-07-09 17:10:25 +0200 [Re: Create LVM
> Volume on Blockdevice]:
> > [...]
> > >Here is the main question, is it possible to create a pv directly
> > >on a block device without having a partition?
> > I am not entirely sure but I think that's possible, yes. I just ran 
> > pvcreate /dev/sda in a test environment and created a VG and LV on
> > top of it just fine.
> 
> yes, manually, it definitely is possible.

yes, i've done that many times. I wanted to achieve that using fai
because it saves time when increasing the size of a virtual disk.
When the pv is directly on the block device you do a pvscan and
everyting is fine. Using a partition table you will have to deal with
that.

> 
> > [...]
> > it appears that everything you want is possible but setup-storage 
> > doesn't support it, yet. I'll try and implement a solution for your 
> > usecase in the upcoming days.
> 
> I don't use setup-storage, but from what I've read on the list
> recently, one idea does spring to mind:

That was my solution as well. I use setup-storage for sda -> /boot
partition + rootvg.
This constellation works very well (but it would also be possible to
get rid of the /boot as a own partition if i would not use
setup-storage here.
sdb gets provisioned by a script (only when a sdb is present), which
works very nice at the moment.

> 
> Stefan Schörghofer wrote on 2015-07-07 15:18:35 +0200 [Create LVM
> Volume on Blockdevice]:
> > [...]
> > My current Diskconfig looks like this:
> > --------------------------------------------------
> > # DATAVG
> > disk_config sdb disklabel:msdos
> > 
> > disk_config lvm
> > vg datavg sdb
> > datavg-datalv /data 8G xfs rw
> > --------------------------------------------------
> 
> What happens if you leave out the "disklabel" part? My guess - from
> what I've read rather than actual experience - is that setup-storage
> would not create a partition table, and consequently pvcreate (or the
> kernel?) would not complain when trying to prepare /dev/sdb for LVM.
> In any case, the "disklabel:msdos" is wrong, strictly speaking,
> because you don't want an msdos partition table on /dev/sdb - you
> want an LVM PV there.

I tried to don't write a partition table. So having just the
disk_config lvm part...it was also not working (sorry..i can't remember
the exact error message)
Kerim Gueney told me already that what I want is currently not possible
using setup-storage but he tries to implement it. So i guess i will
give it a try when the next version is released.

> 
> Hope that helps.
> 
> Regards,
> Holger

Thanks a lot
best regards,
Stefan