Now that GlusterFS 3.7.0 is out, here is the process to upgrade from
earlier installed versions of GlusterFS. Please read the entire howto
before proceeding with an upgrade of your deployment

### Pre-upgrade

GlusterFS contains afrv2 implementation from 3.6.0 by default.If you are
using GlusterFS replication ( \< 3.6) in your setup , please note that
the new afrv2 implementation is only compatible with 3.6 or greater
GlusterFS clients. If you are not updating your clients to GlusterFS
version 3.6 along with your servers you would need to disable client
self healing process before the upgrade. You can perform this by below
steps.

    [root@~]# gluster v set testvol cluster.entry-self-heal off
    volume set: success
    [root@~]#
    [root@~]# gluster v set testvol cluster.data-self-heal off
    volume set: success
    [root@~]# gluster v set testvol cluster.metadata-self-heal off
    volume set: success
    [root@~]#

### GlusterFS upgrade to 3.7.x

**a) Scheduling a downtime**

For this approach, schedule a downtime and prevent all your clients from
accessing (umount your volumes, stop gluster Volumes..etc)the servers.

    1. Stop all glusterd, glusterfsd and glusterfs processes on your server.
    2. Install  GlusterFS 3.7.0
    3. Start glusterd.
    4. Ensure that all started volumes have processes online in “gluster volume status”.

You would need to repeat these steps on all servers that form your
trusted storage pool.

After upgrading the servers, it is recommended to upgrade all client
installations to 3.7.0

**b) Rolling Upgrade [TBD]**

### Special notes for upgrading from 3.4.x to 3.7.X

If you have quota or geo-replication configured in 3.4.x, please read
below. Else you can skip this section.

Architectural changes in Quota & geo-replication were introduced in
Gluster 3.5.0. Hence scheduling a downtime is recommended for upgrading
from 3.4.x to 3.7.x if you have these features enabled.

### **Upgrade Steps For Quota**

The upgrade process for quota involves the following:

1. Run pre-upgrade-script-for-quota.sh
2. Upgrade to 3.7.0
2. Run post-upgrade-script-for-quota.sh

More details on the scripts are as under.

*Pre-Upgrade Script:*

What it does:

The pre-upgrade script (pre-upgrade-script-for-quota.sh) iterates over
the list of volumes that have quota enabled and captures the configured
quota limits for each such volume in a file under
/var/tmp/glusterfs/quota-config-backup/vol\_\<VOLNAME\> by executing
'quota list' command on each one of them.

Pre-requisites for running Pre-Upgrade Script:

1.  Make sure glusterd and the brick processes are running on all nodes
    in the cluster.
2.  The pre-upgrade script must be run prior to upgradation.
3.  The pre-upgrade script must be run on only one of the nodes in the
    cluster.

Location:

pre-upgrade-script-for-quota.sh must be retrieved from the source tree
under the 'extras' directory.

Invocation:

Invoke the script by executing \`./pre-upgrade-script-for-quota.sh\`
from the shell on any one of the nodes in the cluster.

-   Example:

        [root@server1 extras]#./pre-upgrade-script-for-quota.sh

*Post-Upgrade Script:*

What it does:

The post-upgrade script (post-upgrade-script-for-quota.sh) picks the
volumes that have quota enabled.

Because the cluster must be operating at op-version 3 for quota to work,
the 'default-soft-limit' for each of these volumes is set to 80% (which
is its default value) via \`volume set\` operation as an explicit
trigger to bump up the op-version of the cluster and also to trigger a
re-write of volfiles which knocks quota off client volume file.

Once this is done, these volumes are started forcefully using \`volume
start force\` to launch the Quota Daemon on all the nodes.

Thereafter, for each of these volumes, the paths and the limits
configured on them are retrieved from the backed up file
/var/tmp/glusterfs/quota-config-backup/vol\_\<VOLNAME\> and limits are
set on them via the \`quota limit-usage\` interface.

Note:

In the new version of quota, the command \`quota limit-usage\` will fail
if the directory on which quota limit is to be set for a given volume
does not exist. Therefore, it is advised that you create these
directories first before running post-upgrade-script-for-quota.sh if you
want limits to be set on these directories.

Pre-requisites for running Post-Upgrade Script:

1.  The post-upgrade script must be executed after all the nodes in the
    cluster have upgraded.
2.  Also, all the clients accessing the given volume must also be
    upgraded before the script is run.
3.  Make sure glusterd and the brick processes are running on all nodes
    in the cluster post upgrade.
4.  The script must be run from the same node where the pre-upgrade
    script was run.

Location:

post-upgrade-script-for-quota.sh can be found under the 'extras'
directory of the source tree for glusterfs.

Invocation:

post-upgrade-script-for-quota.sh takes one command line argument. This
argument could be one of the following: ''the name of the volume which
has quota enabled; or' '' 'all'.''

In the first case, invoke post-upgrade-script-for-quota.sh from the
shell for each volume with quota enabled, with the name of the volume
passed as an argument in the command-line:

-   Example:

        For a volume "vol1" on which quota is enabled, invoke the script in the following way:
      
        [root@server1 extras]#./post-upgrade-script-for-quota.sh vol1

In the second case, the post-upgrade script picks on its own, the
volumes on which quota is enabled, and executes the post-upgrade
procedure on each one of them. In this case, invoke
post-upgrade-script-for-quota.sh from the shell with 'all' passed as an
argument in the command-line:

-   Example:

        [root@server1 extras]#./post-upgrade-script-for-quota.sh all

Note:

In the second case, post-upgrade-script-for-quota.sh exits prematurely
upon failure to ugprade any given volume. In that case, you may run
post-upgrade-script-for-quota.sh individually (using the volume name as
command line argument) on this volume and also on all volumes appearing
after this volume in the output of \`gluster volume list\`, that have
quota enabled.

The backed up files under /var/tmp/glusterfs/quota-config-backup/ are
retained after the post-upgrade procedure for reference.

### **Upgrade steps for geo replication:**

New version supports only syncing between two gluster volumes via
ssh+gluster.

''Below are the steps to upgrade. ''

​1. Stop the geo-replication session in older version ( \< 3.5) using
the below command

        #gluster volume geo-replication <master_vol> <slave_host>::<slave_vol> stop

​2. Now since the new geo-replication requires gfids of master and slave
volume to be same, generate a file containing the gfids of all the files
in master

        cd /usr/share/glusterfs/scripts/ ;
        bash generate-gfid-file.sh localhost:<master_vol> $PWD/get-gfid.sh    /tmp/master_gfid_file.txt ;
        scp /tmp/master_gfid_file.txt root@<slave_host>:/tmp

​3. Upgrade the slave cluster installation to 3.7.0

​4. Now go to the slave host and apply the gfid to the slave volume.

        cd /usr/share/glusterfs/scripts/
        bash slave-upgrade.sh localhost:<slave_vol> /tmp/master_gfid_file.txt    $PWD/gsync-sync-gfid

This will ask you for password of all the nodes in slave cluster. Please
provide them, if asked. Also note that this will restart your slave
gluster volume (stop and start)

​5. Upgrade the master cluster to 3.7.0

​6. Now create and start the geo-rep session between master and slave.
For instruction on creating new geo-rep session please refer
distributed-geo-rep chapter in admin guide.

        gluster volume geo-replication <master_volume> <slave_host>::<slave_volume> create push-pem force
        gluster volume geo-replication <master_volume> <slave_host>::<slave_volume> start

At this point, your distributed geo-replication should be configured
appropriately.
