[sheepdog-users] Add a new node

[furkan at theshell.co.jp]

Hello,

> * What are the steps to do?

Just run the 4th instance, it will trigger re-balancing of the objects.
Depending on your data size, this will create a big network and storage
load for creating new copies or moving existing objects around.

> * Do I need to switch off the cluster ?

No. Try not to switch off your cluster ever.

> * Zookeeper is installed on 3 nodes, I need its installation also on
> the 4° node?

No zookeeper does not need to scale along with sheepdog.

> * When I created the cluster I specified --copies 2, with the 4°
> node i would like to change with --copies 3. Is it possibile?

This setting is different for each volume. For cluster I *think* you can
change the number of copies.

The most important part;

> The cluster is in production

Sheepdog is not that much production-ready (IMO), be sure to keep
backups periodically depending on your data's criticality.

I still could not get any help for my huge troubles for recovering my
sheepdog cluster.

Another note; If you're using sheepdog for VMs, I'd suggest pausing/
suspending your vms before adding the new node. And resume them after
the recovery is complete.

Every time you add/remove a node, recovery will need to work to move
the objects to their designated places. And 'not modifying the
objects/volumes' while they move, is a good idea for sheepdog I think.
I have corrupted my volumes really badly because of this (I think).

I keep a terminal running `watch --interval=10 dog node recovery` for
watching recovery(or re-balance) status.

Furkan Mustafa

On 2018-03-08 00:23, Cristian Del Carlo wrote:
> Hi,
> 
> I have a cluster with 3 nodes.
> All nodes are installed with centos 7.X, zookeeper 3.4.6 e sheepdog
> 1.0.1.
> The cluster is in production so I would like to be sure of the
> operations to be done.
> 
> I need to add the 4° node. I have several doubts about which I would
> like some advice:
> 
> 	* What are the steps to do?
> 	* Do I need to switch off the cluster ?
> 	* Zookeeper is installed on 3 nodes, I need its installation also on
> the 4° node?
> 
> 	* When I created the cluster I specified --copies 2, with the 4°
> node i would like to change with --copies 3. Is it possibile?
> 
> Thanks in advance for your advice.
> 
> _CRISTIAN DEL CARLO_