[Engine-devel] Migrating an existing installation to hosted engine

[Michal Skrivanek]

On Nov 12, 2013, at 12:38 , Yedidyah Bar David <didi at redhat.com> wrote:

> Hi all,
> 
> A message with the same subject was sent to arch around a month ago, see [1].
> 
> In short, it suggested two approaches:
> 1. Use p2v (or v2v)
> 2. Clean install of OS/engine software and use backup/restore.
> 
> Following that, I pushed a few changes for engine-backup and engine-setup,
> with the intention of doing, briefly:
> 1. hosted-engine --deploy on new host
> 2. Install OS/software on new vm
> 3. backup on old engine machine
> 4. On new vm, do restore, which only restores the database and files,
> followed by engine-setup, which will fix whatever else needs to be fixed.
> 
> Some of the changes are still pending, and are under some controversy. See
> [2], [3], [4].
> 
> A more detailed description of the suggested migration path is in [5].
> 
> What do you think?
> 
> Should engine-setup do as little as possible to the system, or as much as
> needed to save the admin from any manual work?
> 
> Should engine-setup doing an upgrade do the same as a new setup, or just
> whatever that's needed to adapt the config/database to the new code?
> 
> A specific example: if admin chose during initial setup to automatically
> configure the firewall (iptables/firewalld), should upgrade update it again,
> or not touch it?
> 
> Should engine-backup do all these things when doing a restore?

I think using the same tool for both tasks(backup, migration to hosted engine) has an advantage that you only address issues (like missing item to backup/restore) once and both usecases benefit from a fix

> 
> Should we have some other utility to do these things?
> 
> Should we merely document them and let the admin do this manually?
> 
> [1] http://lists.ovirt.org/pipermail/arch/2013-October/001677.html
> [2] https://bugzilla.redhat.com/1024707
> [3] http://gerrit.ovirt.org/20736
> [4] http://gerrit.ovirt.org/20737
> [5] http://www.ovirt.org/Migrate_to_Hosted_Engine
> -- 
> Didi
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