GFS2 Storage:
==============

Desc:
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Shared Disk File system for iSCSI storage pools (Red Hat).

Instructions:
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NOTE : THESE ARE UNTESTED INSTRUCTIONS !!!

Add the iSCSI target to each server.

Start the iSCSI on both servers but format the pool from one server only.

Required packages:
  pacemaker - cluster resource manager
  pcs - Pacemaker Configuration System
  lvm2 - Linux Logical Volume Manager

apt install pacemaker pcs lvm2

setup cluster:
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https://www.redhat.com/sysadmin/rhel-pacemaker-cluster

# Create the 'hacluster' user
passwd hacluster

# start pacemaker
systemctl enable pcsd.service
systemctl start pcsd.service

# connect to other nodes
pcs cluster auth node1.example.com node2.example.com

# create cluster
pcs cluster setup --name gfs2 node1 node2

# start cluster
pcs cluster start --all

# Enable the cluster to auto-start after reboot
pcs cluster enable --all

setup gfs2:
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https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/global_file_system_2/ch-clustsetup-gfs2

# set pacemaker no-quorum-policy to freeze
pcs property set no-quorum-policy=freeze

# Set up a dlm resource. This is a required dependency for clvmd and gfs2
pcs resource create dlm ocf:pacemaker:controld op monitor interval=30s on-fail=fence clone interleave=true ordered=true

# enable the cluster
/usr/sbin/lvmconf --enable-cluster

# Set up clvmd as a cluster resource.
pcs resource create clvmd ocf:heartbeat:clvm op monitor interval=30s on-fail=fence clone interleave=true ordered=true

# Set up clvmd and dlm dependency and start up order. clvmd must start after dlm and must run on the same node as dlm
pcs constraint order start dlm-clone then clvmd-clone
pcs constraint colocation add clvmd-clone with dlm-clone

# Create the clustered logical volume (where ? is the iSCSI target mapped to a device)
# Should use /dev/disk/by-path/??? since the /dev/sd? is mapped on demand and can change
pvcreate /dev/sd?
vgcreate -Ay -cy gfs2_vg /dev/sd?
lvcreate -L5G -n gfs2_lv gfs2_vg

# format the filesystem
mkfs.gfs2 -j2 -p lock_dlm -t cluster:gfs2 /dev/gfs2_vg/gfs2_lv

# Configure a clusterfs resource.
pcs resource create clusterfs Filesystem device="/dev/gfs2_vg/gfs2_lv" directory="/volumes/gfs2" fstype="gfs2" options="noatime" op monitor interval=10s on-fail=fence clone interleave=true

# Set up GFS2 and clvmd dependency and startup order.
# GFS2 must start after clvmd and must run on the same node as clvmd.
pcs constraint order start clvmd-clone then clusterfs-clone
pcs constraint colocation add clusterfs-clone with clvmd-clone

# Now you should be able to mount the volume on both servers.

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