[Gluster-users] Upgrade Gluster 3.7 to 3.12 and add 3rd replica [howto/help]

Martin Toth snowmailer at gmail.com
Sun Oct 1 15:53:57 UTC 2017

Hi Diego,

I’ve tried to upgrade and then extend gluster with 3rd node in virtualbox test environment and all went without problems.
Sharding will not help me at this time so I will consider upgrading 1G to 10G before this procedure in production. That should lower downtime - healing time of VM image files on Gluster.

I hope healing will take as short as possible on 10G.

Additional info for Gluster/Qemu Users:
- Ubuntu does not have Qemu compiled with libgfapi support so I’ve created PPA for that :
	https://launchpad.net/~snowmanko/+archive/ubuntu/qemu-glusterfs-3.12 <https://launchpad.net/~snowmanko/+archive/ubuntu/qemu-glusterfs-3.12> (I will try to make this repo up to date)
	- it’s tested against glusterfs3.12.1 version (libgfapi works as expected with this repo)

- Moreover related to this problem - there is MIR - https://bugs.launchpad.net/ubuntu/+source/glusterfs/+bug/1274247 <https://bugs.launchpad.net/ubuntu/+source/glusterfs/+bug/1274247> - it’s now accepted, I am really excited to see libgfapi compiled by default in Ubuntu Qemu packages in near future

Thanks for support.



> On 22 Sep 2017, at 14:50, Diego Remolina <dijuremo at gmail.com> wrote:
> Hi Martin,
>> 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.
> When you switch to PPA, make sure to download and keep a copy of each
> set of gluster deb packages, otherwise if you ever want to back out an
> upgrade to an older release, you will have to download the source deb
> file and build it yourself, because PPAs only keep the latest version
> for binaries.
>> 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 ?
> Sharding is not so much about brick size. Sharding is about preventing
> a whole large VM file being locked when it is being healed. Also
> minimizes the amount of data copied because gluster only heals smaller
> pieces versus a whole VM image.
> Say your 100GB IMG needs to be healed, the file is locked while it
> gets copied from one server to the other and the running VM may not be
> able to use it while the heal is going, so your VM may in fact stop
> working or have I/O errors. With sharding, VMs are cut into, well,
> shards, largest shard is 512MB, then the heal process only locks the
> shards being healed. So gluster only heals the shards that changed
> which are much smaller and faster to copy, and do not need to lock the
> whole 100GB IMG file which takes longer to copy, just the shard being
> healed. Do note that if you had never used sharding, if you turn it on
> it will *not* convert your older files. Also you should *never* turn
> on sharding and then back off, as that will result in corrupted VM
> image files. Once it is on, if you want to turn it off, stop your VMs,
> then move all VM IMG files elsewhere, turn off sharding and then copy
> the files back  to the volume after disabling sharding.
> As for speed, I really cannot tell you as it depends on the disks,
> netowr, etc. For example, I have a two node setup plus an arbiter (2
> nodes with bricks, one is just the arbiter to keep quorum if one of
> the brick servers goes down). I recently replaced the HDDs in one
> machine as the drives hit the 5 year age mark. So I took the 12 drives
> out, added 24 drives to the machine (we had unused slots),
> reconfigured raid 6 and left it initializing in the background and
> started the heal of 13.1TB of data. My servers are connected via
> 10Gbit (I am not seeing reads/writes over 112MB/s) and this process
> started last Monday at 7;20PM and it is not done yet. It is missing
> healing about 40GB still. Now my servers are used as a file server,
> which means lots of small files which take longer to heal. I would
> think your VM images will heal much faster.
>> 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).
> You could even attempt an online upgrade if you try to add the new
> node/brick running 3.12 to the mix before upgrading from 3.7.x on the
> other nodes. However, I am not sure how that is going to work. With
> such a difference in versions, it may not work well.
> If you can afford the downtime to upgrade, that will be the safest option.
> Diego

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