Re: Google App Engine Master/Slave Datastore Deprecation

[Joshua Smith]

Yeah, yeah, I know that many of my old M/S applications are running on the officially deprecated database. And I know that they might suffer a little more downtime as a result. But I also know that they are working just fine, and I'm not particularly interested in going through the pain of migrating (particularly working around all those annoying consistency things -- I've done that twice now, and each time it took quite a lot of programming to hide this stuff from the users).

So the question: Is this notice just a helpful reminder, or is there an implicit "or else" between the lines that I'm not seeing?

-Joshua

On Aug 24, 2012, at 9:10 AM, Google App Engine <appengin...@google.com> wrote:

Dear App Engine Developer,

We’ve noticed that you are running at least one application configured to use the Master/Slave (M/S) datastore. This application configuration was officially deprecated on April 4, 2012, in accordance with our deprecation policy, in favor of the more reliable High Replication Datastore (HRD). HRD uses the Paxos algorithm to serve your application out of multiple datacenters, meaning better redundancy in the face of datacenter issues, more consistent datastore performance, and no planned downtime.

When we deprecated the M/S datastore, we introduced a migration tool that allows you to easily migrate all your datastore and blobstore data to a new HRD application. Migrating your application will not require you to change your application’s URL, whether it serves from appspot.com or a custom domin. Please note that even if your application does not store any data in the datastore, it will still benefit from the automated datacenter failover that is only available to HRD applications.

Before migrating your application, you should read about the differences between M/S and HRD, and understand how the consistency policy for HRD might affect the queries in your application.

All HRD applications that have billing enabled are covered by App Engine’s 99.95% uptime SLA. Along with the substantial reliability improvements, many new App Engine features are only being made available to HRD applications, including the Python 2.7 language option, Full Text Search (FTS), and Page Speed integration.

We strongly encourage you to migrate your applications as soon as possible. If you have technical questions about HRD or the migration process, you can post them to Stack Overflow. Any general migration discussions can be posted to our Google Group.


Thank You,

The App Engine Team

© 2012 Google Inc. 1600 Amphitheatre Parkway, Mountain View, CA 94043
You have received this mandatory email service announcement to update you about important changes to your Google App Engine account.

[Barry Hunter]

While it appears M/S should be around until April 20, 2015 - guessing Google are just trying to push people over. 

The less time they can spend applying band-aids to the M/S serving infestructure (and also many new features still have to be be tested against M/S - the code common to the two platforms) - the more time they can work on new stuff. 

It's not a 'threat', its a begging letter. They want to kill M/S sooner*.

*(and I imagine it will happen. Keeping M/S will become a serious material technical burden before 2015. )

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[Sargis Dallakyan]

Thanks for the discussion. Now I understand this from Google's perspective, but it's no clear what happens if I do not migrate. Will all my data be lost? Thanks.

[Barry Hunter]

Its probably not decided yet. 

The ideal for Google would be to get down to nobody using M/S - ie 0 active applications. Then it can just be turned off and nobody will even notice. This avoids the issue completely. 

Thats unrealistic, so the more people they can beg to move - the easier the tough decision to kill it will be. But it almost certainly will come, so the sooner you move, the less chance your application will suddenly disappear. 

If they just turned it off, then yes data would probably be "gone". Might still be on a google server somewhere, on a storage device. But will be inaccessible, and useless. 

If there are suffienct people still using it when the decisision is made, they may decide its worth the effort to archive the data somewhere. Make a backup in Google Storage or something, and let the developer access that 'last backup'. The application will already be dead by then. 

It all comes down to risk - how long can your nerve hold out :)

To view this discussion on the web visit https://groups.google.com/d/msg/google-appengine/-/OPEkcgiWaKIJ.