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From ilya <ilya.mailing.li...@gmail.com>
Subject Re: Help with migrating primary storage (NFS) from Zone to Cluster scope
Date Thu, 11 Feb 2016 23:21:37 GMT
Rohan

This is the first time i'm seeing this question.

Here is how i would try to migrate this over, ideally - i'd spend few
hours setting up a demo lab environment to see how things work out.

With that said, i believe it wont be too complicated, but i'd not do it
in production without testing the lab first.

In the lab, do the same setup as you have in prod, you can even do the
whole lab setup on 1 VM, though few VMs would be ideal.

Limit any changes to ACS
Enable MYSQL Query logging, add cluster level storage
Inspect any inserts and updates that a relevant
Migrate global storage to cluster level scope storage in your lab
Run basic tests to confirm it works

Regards
ilya

On 2/10/16 7:39 PM, Rohan T wrote:
> Hi all,
> 
> 
> We're attempting to make a production change to a CloudStack deployment
> (currently installed at 4.4.1), where we want to change the scope of the
> attached primary storage from being attached at ZONE scope to CLUSTER scope
> (this deployment currently has exactly 1 zone, 1 pod and 1 cluster in use).
> 
> The purpose of the change is to allow us to deploy a second primary storage
> device to a new cluster, providing no single points of failure within the
> system.
> 
> (Note: adding 2 primary storage devices to the same zone has had the
> opposite effect, effectively halving the reliability of the system since
> each node considers failure of _any_ NFS primary storage to be sufficient
> grounds to initiate a HA reboot event).
> 
> All VM's are KVM, all used storage is NFS shared storage.  There are dozens
> of deployed VM's running and 20 hosts deployed.
> 
> The expectation is that this change would be made during a system
> maintenance event (and shutdown), but the hope is that we can effect this
> change without complete removal of the storage and associated redeployment
> of all VMs.
> 
> I note that the design notes for 4.2 (where storage scope was introduced),
> indicate that the major design change that needs to be accounted for was
> the that a column, called scope, was added into storage_pool table.
> (see:
> https://cwiki.apache.org/confluence/display/CLOUDSTACK/Zone-wide+primary+storage+target
> ).
> 
> This suggests that the change could be as trivial as:
> 0. Shutdown of cloudstack management server.
> 1.  Identifying the primary storage device in cloud.storage_pool.
> 2.  Changing the 'scope' field from 'ZONE' to 'CLUSTER'.
> 3.  Populating the 'pod_id' and 'cluster_id' fields to reflect the
> appropriate pod & cluster.
> 4.  Restart cloudstack.
> 
> Questions:
> 
> 1. Has anyone attempted a similar migration?
> 2. Is this the way it's designed to work (in 4.4.1)?  Are there any other
> values to be accounted for?
> 3. Is there another way to effect this through an API/UI? (We would
> consider an upgrade if this is supported in a later release)?
> 
> 
> 
> Thanks in advance,
> 
> Rohan
> 

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