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Re: [linux-lvm] LVM1 on top of DRBD



On Wed, Aug 20, 2003 at 01:54:36PM +0200, Joachim Banzhaf wrote:
> Am Mittwoch, 20. August 2003 12:46 schrieb Heinz J . Mauelshagen:
> > Joachim,
> 
> First, thanks for your quick response, Heinz.
> 
> > LVM1 isn't cluster aware.
> 
> I knew that - as I stated, I read the FAQ :-).
> 
> > DRBD devices are just some other "local" ones for it.
> 
> OK, but as i stated, I used them that way. LVM1 just seems to use the lower 
> level devices drbd works on instead. That's what's bothering me.

Ah, missed that point :(
LVM2 is your better option because it supports device name filters
in a config file rather than hard-coded ones.

> To make clear what I mean, here some details:
> 
> I have /dev/nb1 as resource lvm1 on top of /dev/sdb1 in /etc/drbd.conf
<SNIP>
> devices and used despite of pvcreate commandline options.
> As I stated, to follow this hypothesis I used a patch to make lvm tools ignore 
> the partitions /dev/sdbx.
> The vgdisplay output then shows the nbx devices (even without vgscan'ning or 
> something). But they are not used by the kernel anyway as I see no activity 
> on /proc/drbd :-(
> 
> > No replication is done by LVM1.
> 
> Yes, that's why I use drbd :-)
> 
> > The whole replication process is up to DRBD, that's why you
> > need to start it using a DRBD command.
> >
> > You can use hartbeat to recognize if a node dies and scripts to start LVM
> > on the living node to access logical volumes there.
> 
> I have a fully working set of linux, lvm1, heartbeat and drbd with services on 
> top. I know how they work (from a user/admin perspective - and a bit more).
> And they work fine for me (including failovers of course) as long as I use 
> drbd resources on top of lv's. 
> But I want to use drbd resources as pv's.
> That seems not to work, because LVM1 persists in using the partition and not 
> the drbd network block device although I configured it that way (as stated my 
> original post).
> 
> Again, to clear the ground: Should it be possible at all to use pv's on top of 
> drbd devices or am I forced to use drbd devices on top of lv's and loose 
> things like online resize feature?
> 
> Have you - or anybody reading the list - ever sucessfully used that scenario? 

I don't. List ?

> 
> > Regards,
> > Heinz    -- The LVM Guy --
> >
> > On Wed, Aug 20, 2003 at 11:41:20AM +0200, Joachim Banzhaf wrote:
> > > Hi list,
> > >
> > > I'd like to use LVM1 on top of DRBD 0.6.6 and not the other way round,
> > > because I then can resize my partitions online (add a new drbd device,
> > > make it a pv, add it to a vg, be happy).
> > >
> > > It just seems not to be that simple.
> > >
> > > The HOWTO warns about LVM not being cluster aware and describes how to do
> > > it anyway on shared storage. I (think I) have these requirements met by
> > > using heartbeat to have vg's active at one node only and running vgscan
> > > on the secondary after changes on the primary.
> > >
> > > I created the pv's using the /dev/nbx devices (x=1,2).
> > > I created the vg lvm-drbd with lv lv1-s2 using these pv's.
> > >
> > > The corresponding haresources file is this:
> > > job-vm1 192.168.1.101 datadisk::lvm1 datadisk::lvm2 LVM::lvm-drbd \
> > >   Filesystem::/dev/lvm-drbd/lv1-s2::/ha/export::reiserfs
> > >
> > > What I get is lvm using the lower level device (sdbx in my case).
> > > vgdisplay -vD shows the pv's using /dev/sdbx.
> > > Nothing gets replicated to the other node (not surprising then).
> > > I even patched lvm_check_dev.c and rebuilt the lvm tools to ignore
> > > /dev/sdbx devices, removed all lvm infos from /etc and did a new vgscan
> > > and vgcfgbackup. vgdisplay -vD now shows the /dev/nbx devices for the
> > > pv's. But still no replication without drbdsetup /dev/nbx replicate :-(.
> > >
> > > I use suse 8.2 with suse 2.4.20-4GB kernel (you'ed a few weeks ago)
> > > for the lvm_check_dev.c-patch I installed the lvm source rpm, modified
> > > the spec file not to use the mp patches (because a file was missing),
> > > added my patchfile and did a rpm -bi /usr/src/packages/SPECS/lvm.spec.
> > >
> > > Btw. the build process did not stop on compile errors in lvm_check_dev.c.
> > > Is that intended? It is confusing...
> > >
> > > What am I doing wrong?
> > > Is it possible doing LVM on top of DRBD at all?
> > >
> > > I'd happily provide more details if it helps.
> > >
> > > Ciao,
> > >
> > > Joachim Banzhaf
> > >
> > >
> > > _______________________________________________
> > > linux-lvm mailing list
> > > linux-lvm sistina com
> > > http://lists.sistina.com/mailman/listinfo/linux-lvm
> > > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> >
> > *** Software bugs are stupid.
> >     Nevertheless it needs not so stupid people to solve them ***
> >
> > _______________________________________________
> > linux-lvm mailing list
> > linux-lvm sistina com
> > http://lists.sistina.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm sistina com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen Sistina com                           +49 2626 141200
                                                       FAX 924446
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