Re: Upgrade Gluster 3.7 to 3.12 and add 3rd replica [howto/help]

Martin Toth <snowmailer@xxxxxxxxx> · Fri, 22 Sep 2017 14:22:05 +0200

Hi, 
thanks for suggesions. Yes "gluster peer probe node3” will be first command in order to discover 3rd node by Gluster.
I am running on latest 3.7.x - there is 3.7.6-1ubuntu1 installed and latest 3.7.x according https://packages.ubuntu.com/xenial/glusterfs-server is 3.7.6-1ubuntu1, so this should be OK.

If you are *not* on the latest 3.7.x, you are unlikely to be able to go
Do you mean latest package from Ubuntu repository or latest package from Gluster PPA (3.7.20-ubuntu1~xenial1). 
Currently I am using Ubuntu repository package, but want to use PPA for upgrade because Ubuntu has old packages of Gluster in repo.

I do not use sharding because all bricks has same size, so it will not speedup healing of VMs images in case of heal operation. Volume is 3TB, how long does it take to heal on 2x1gbit (linux bond) connection, can you approximate ? 
I want to turn every VM off because its required for upgrading gluster procedure, thats why I want to add 3rd brick (3rd replica) at this time (after upgrade when VMs will be offline).

Martin

On 22 Sep 2017, at 12:20, Diego Remolina <dijuremo@xxxxxxxxx> wrote:

Procedure looks good.
Remember to back up Gluster config files before update:

/etc/glusterfs
/var/lib/glusterd

If you are *not* on the latest 3.7.x, you are unlikely to be able to go back to it because PPA only keeps the latest version of each major branch, so keep that in mind. With Ubuntu, every time you update, make sure to download and keep a manual copy of the .Deb files. Otherwise you will have to compile the packages yourself in the event you wanted to go back.

Might need before adding 3rd replica:
gluster peer probe node3 

When you add the 3rd replica, it should start healing, and there may be an issue there if the VMs are running. Your plan to not have VMs up is good here. Are you using sharding? If you are not sharding, I/O in running VMs may be stopped for too long while a large image is healed. If you were already using sharding you should be able to add the 3rd replica when VMs are running without much issue.

Once healing is completed and if you are satisfied with 3.12, then remember to bump op version of Gluster.

Diego

On Sep 20, 2017 19:32, "Martin Toth" <snowmailer@xxxxxxxxx> wrote:
Hello all fellow GlusterFriends,

I would like you to comment / correct my upgrade procedure steps on replica 2 volume of 3.7.x gluster.
Than I would like to change replica 2 to replica 3 in order to correct quorum issue that Infrastructure currently has.

Infrastructure setup:
- all clients running on same nodes as servers (FUSE mounts)
- under gluster there is ZFS pool running as raidz2 with SSD ZLOG/ZIL cache
- all two hypervisor running as GlusterFS nodes and also Qemu compute nodes (Ubuntu 16.04 LTS)
- we are running Qemu VMs that accesses VMs disks via gfapi (Opennebula)
- we currently run : 1x2 , Type: Replicate volume

Current Versions :
glusterfs-* [package] 3.7.6-1ubuntu1
qemu-*		[package] 2.5+dfsg-5ubuntu10.2glusterfs3.7.14xenial1

What we need : (New versions)
- upgrade GlusterFS to 3.12 LTM version (Ubuntu 16.06 LTS packages are EOL - see https://www.gluster.org/community/release-schedule/)
	- I want to use https://launchpad.net/~gluster/+archive/ubuntu/glusterfs-3.12 as package repository for 3.12
- upgrade Qemu (with build-in support for libgfapi) - https://launchpad.net/~monotek/+archive/ubuntu/qemu-glusterfs-3.12
	- (sadly Ubuntu has packages build without libgfapi support)
- add third node to replica setup of volume (this is probably most dangerous operation)

Backup Phase
- backup "NFS storage” - raw DATA that runs on VMs
- stop all running VMs
- backup all running VMs (Qcow2 images) outside of gluster

Upgrading Gluster Phase
- killall glusterfs glusterfsd glusterd (on every server)
	(this should stop all gluster services - server and client as it runs on same nodes)
- install new Gluster Server and Client packages from repository mentioned upper (on every server) 
- install new Monotek's qemu glusterfs package with gfapi enabled support (on every server) 
- /etc/init.d/glusterfs-server start (on every server)
- /etc/init.d/glusterfs-server status - verify that all runs ok (on every server)
	- check :
		- gluster volume info
		- gluster volume status
		- check gluster FUSE clients, if mounts working as expected
- test if various VMs are able tu boot and run as expected (if libgfapi works in Qemu)
- reboot all nodes - do system upgrade of packages
- test and check again

Adding third node to replica 2 setup (replica 2 => replica 3)
(volumes will be mounted and up after upgrade and we tested VMs are able to be served with libgfapi = upgrade of gluster sucessfuly completed)
(next we extend replica 2 to replica 3 while volumes are mounted but no data is touched = no running VMs, only glusterfs servers and clients on nodes)
- issue command : gluster volume add-brick volume replica 3 node3.san:/tank/gluster/brick1 (on new single node - node3)
	so we change : 
		Bricks:
			Brick1: node1.san:/tank/gluster/brick1
			Brick2: node2.san:/tank/gluster/brick1
	to :
			Bricks:
			Brick1: node1.san:/tank/gluster/brick1
			Brick2: node2.san:/tank/gluster/brick1
			Brick3: node3.san:/tank/gluster/brick1
- check gluster status
- (is rebalance / heal required here ?)
- start all VMs and start celebration :)

My Questions
- is heal and rebalance necessary in order to upgrade replica 2 to replica 3 ?
- is this upgrade procedure OK ? What more/else should I do in order to do this upgrade correctly ?

Many thanks to all for support. Hope my little preparation howto will help others to solve same situation.

Best Regards,
Martin

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