Re: Shared VG, Separate LVs

[Eric Ren <zren@suse.com>]

Had a look at your setup, I have one question:

Did you check if your active-passive model HA stack can always work correctly and stably by
putting one node into offline state?

I noticed you didn't configure LVM resource agent to manage your VG's (de)activation task,
not sure if it can always work as expect, so have more exceptional checking :)

Eric

On 11/03/2017 02:38 PM, Indivar Nair wrote:

Hi Eric, All,

Thanks for the input. I have got it working. 

Here is what I did -

-------------------------------------------------------------------------------------------------------------------------------------------------------

Cluster Setup:

2 Nodes with CentOS 7.x: clstr01-nd01, clstr01-nd02

Common storage array between both nodes (8 shared volumes, presented as /dev/mapper/mpatha to /dev/mapper/mpathh)

2 Port NICs, bonded (bond0) in each node

Resource group grp_xxx (nd01 preferred) - 

Mount Point: /clstr01-xxx 

Cluster IP: 172.16.0.101/24

Resource group grp_yyy (nd02 preferred) - 

Mount Point: /clstr01-yyy

Cluster IP: 172.16.0.102/24

On both nodes:

--------------

Edit /etc/lvm/lvm.conf, and configure 'filter' and 'global_filter' parameters to scan only the required (local and shared) devices.

Then run - 

# /sbin/lvmconf --enable-cluster

Rebuild initramfs - 

# mv /boot/initramfs-$(uname -r).img /boot/initramfs-$(uname -r).img-orig

# dracut -H -f /boot/initramfs-$(uname -r).img $(uname -r)

Reboot both nodes.

--------------

After rebooting both nodes, run the following commands on any one node:

--------------

# pcs cluster start --all

# pcs resource create dlm ocf:pacemaker:controld op monitor interval=30s on-fail=fence clone interleave=true ordered=true

# pcs resource create clvmd ocf:heartbeat:clvm op monitor interval=30s on-fail=fence clone interleave=true ordered=true

# pcs constraint order start dlm-clone then clvmd-clone

# pcs constraint colocation add clvmd-clone with dlm-clone

# pvcreate /dev/mapper/mpath{a,b,c,d,e,f,g,h}

# vgcreate -Ay -cy clstr_vg01 /dev/mapper/mpath{a,b,c,d,e,f,g,h}

# lvcreate -L 100T -n lv01 clstr_vg01

# mkfs.xfs /dev/clstr_vg01/lv01

# lvcreate -L 100T -n lv02 clstr_vg01

# mkfs.xfs /dev/clstr_vg01/lv02

# pcs resource create xxx_mount ocf:heartbeat:Filesystem device=/dev/clstr_vg01/lv01 directory=/clstr01-xxx fstype=xfs --group xxx_grp --disabled

# pcs resource create xxx_ip_01 ocf:heartbeat:IPaddr2 ip=172.16.0.101 cidr_netmask=24 nic=bond0:0 op monitor interval=30s --group xxx_grp --disabled

# pcs constraint location xxx_grp prefers clstr01-nd01=50

# pcs constraint order start clvmd-clone then xxx_grp

# pcs resource enable xxx_mount

# pcs resource enable xxx_ip_01

# pcs resource create yyy_mount ocf:heartbeat:Filesystem device=/dev/clstr_vg01/lv02 directory=/clstr01-yyy fstype=xfs --group yyy_grp --disabled

# pcs resource create yyy_ip_01 ocf:heartbeat:IPaddr2 ip=172.16.0.102 cidr_netmask=24 nic=bond0:1 op monitor interval=30s --group yyy_grp --disabled

# pcs constraint location yyy_grp prefers clstr01-nd02=50

# pcs constraint order start clvmd-clone then yyy_grp

# pcs resource enable yyy_mount

# pcs resource enable yyy_ip_01

--------------

# pcs resource show

--------------

-------------------------------------------------------------------------------------------------------------------------------------------------------

Regards,

Indivar Nair

On Mon, Oct 16, 2017 at 8:36 AM, Eric Ren <zren@suse.com> wrote:

Hi,

On 10/13/2017 06:40 PM, Indivar Nair wrote:

Thanks Eric,

I want to keep a single VG so that I can get the bandwidth (LVM Striping) of all the disks (PVs)  

  PLUS 

the flexibility to adjust the space allocation between both LVs. Each LV will be used by  different departments. With 1 LV on different hosts, I can distribute the Network Bandwidth too.

I would also like to take snapshots of each LV before backing up.

I have been reading more about CLVM+Pacemaker options.

I can see that it is possible to have the same VG activated on multiple hosts for a GFSv2 filesystem.

In which case, it is the same PVs, VG and LV getting activated on all hosts.

OK! It sounds reasonable.

In my case, we will have the same PVs and VG activated on both hosts, but LV1 on Host01 and LV2 on Host02. I paln to use ext4 or XFS filesystems.

Is there some possibility that it would work?

As said in the last mail, the new resource agent [4] will probably work for you, but I didn't test this case yet. It's easy to have a try - the RA is just shell
script, you can just copy LVM-activate to /usr/lib/ocf/resource.d/heartbeat/ (assume you've installed resource-agents package), and then configure
"clvm + LVM-activate" for pacemaker [5]. Please report back if it doesn't work for you.

The LVM-activate RA is WIP. We are thinking if we should merge it into the old LVM RA. So it may changes at any time.

[5] https://www.suse.com/documentation/sle-ha-12/book_sleha/data/sec_ha_clvm_config.html

[1] https://github.com/ClusterLabs/resource-agents/blob/master/heartbeat/clvm
[2] https://github.com/ClusterLabs/resource-agents/blob/master/heartbeat/LVM
[3] https://www.redhat.com/archives/linux-lvm/2017-January/msg00025.html
[4] https://github.com/ClusterLabs/resource-agents/pull/1040\

Eric

_______________________________________________
linux-lvm mailing list
linux-lvm@redhat.com
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

_______________________________________________
linux-lvm mailing list
linux-lvm@redhat.com
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/