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

[Blaise Alleyne]

On 09/04/15 02:09 PM, Christopher Baines wrote:
> On 09/04/15 09:55, Elena ``of Valhalla'' wrote:
>> On 2015-04-09 at 00:28:00 +0100, Christopher Baines wrote:
>>> 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.
>>
>> I'm not sure that this would work in the case when the migration is not
>> between an old live server and a newer one, because of planned updates,
>> but between the backups of an old dead server and a new one, because 
>> of emergency replacement. I suspect that home servers may tend to fall 
>> in this case more often than "traditional" servers with an
>> administrator.
> 
> Yep, I agree that it would not work, but I still think it would be a
> valuable feature.
> 
> Dealing with restoring a application from a backup is very dependent on
> the representation of the backup, and this is not something I know much
> about.
> 
> It seems to me that this is important, but in my opinion should be
> ignored when thinking about "moving from one server to another.
> 
> 

Interesting. Basically, import/export functionality. WordPress is pretty good at
this, for example...

But yeah, you've got lots of additional complications in moving server to
server... e.g. even with an application like WordPress that has pretty decent
"import from another WordPress instance" functionality, if you're moving from
one server to another, how can you point the new instance to the old instance?
You'd have to have it available by IP (which would be even tougher if there's
some virtual host setup), or set up some temporary subdomain for the new
instance and then switch or something... you'd need some way of having both
instances available that I'm not sure would be straightforward to automate,
you're still dealing with the DNS or virtual hosts or something that involves
some sysadmin skills...

I'm not sure if application-level stuff really solves the server migration issue
either... BUT, wouldn't it be awesome if as a general best practice,
applications (a) had their own backup/export functionality, and (b) have their
own import functionality, that could work off an backup/export *or* by
connecting to another instance?

Even if that wouldn't fix the problem of server migration, it'd certainly make a
lot of server migration subroutines a *lot* easier...