Re: [Userops] Why is it hard to move from one machine to another? An analysis.

[Christopher Baines]

On 08/04/15 16:22, Christopher Allan Webber wrote:
> Hello all,
> 
> For a while I've been considering, why is it so harder for me to migrate
> from server to server than it is for me to migrate from desktop to
> desktop?  For years, ever since I discovered rsync, migrating between
> machines has not been hard.  I simply rsync my home directory over to
> the new machine (or maybe even just keep the old /home/ directory's
> partition where it is!) and bam, I am done.  Backing this up is easy;
> it's just another rsync away.  (I use dirvish as a simple wrapper around
> rsync so it can manage incremental backups.)
> 
> If I set up a new machine, it is no worry.  Even if my current machine
> dies, it is *mostly* no worry.  Rsync back my home directory, and done.
> I will spend a week or so discovering that certain programs I rely on
> are not there, and I'll install them one by one.  In a way it's
> refreshing: I can install the programs I need, and the old cruft is
> gone!
> 
> This is not true for servers.  At the back of my mind I realized this,
> but until the end of Stefano Zacchiroli's excellent LibrePlanet talk
> when I posed a question surrounding this situation, I hadn't totally
> congealed in my head: *why* is it so much harder for me to move from
> server to server?  Assume I even have the old server around and I want
> to move.  It isn't easy!

I agree that its not easy, and I think one approach could look like this.

You have an old server (in terms of hardware and software versions), and
you want to replace it with a new server, all the applications and data
should be moved.

I think the old guaranteed way of making this work is to allow
applications to handle the migration themselves, otherwise you could run
in to incompatibilities in the software versions.

Therefore, for applications that require it, the application must be
able to talk to another instance, and grab the data and config. For
simpler applications, this could just be rsync.

For some systems, this might be quite easy. For example, I am told that
with Cozy cloud, you just add the new server and a client on the old
server, let it sync, and then take the old server off line (I believe it
uses some couchdb stuff internally).

Then you probably need some support in whatever application management
system you are using, whether that be FreedomBox or Sandstorm.
Effectively it is just another application, but it migrating means that
it will install all the applications that were on the old server, and
instruct them to migrate.

The only personal experience I have of this, is that I am currently
putting off migrating my tt-rss instance because I think I might have to
manually move the database across. What I really want to be able to do
is just sudo apt install tt-rss on the new machine, login, and give it
the credentials to the old machine, and have it do all the hard work.

This could be an area in which Mediagoblin pushes out in to? Would a
migration feature like I describe above work for Mediagoblin?

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