Kyle, Oy, I wish you had posted earlier. We've shipped a new migration tool as part of 1.6.1 that doesn't use datastore admin to do the copies.
-- Ikai Lan Developer Programs Engineer, Google App Engine plus.ikailan.com | twitter.com/ikai On Sun, Dec 11, 2011 at 6:38 PM, Kyle Baley <k...@baley.org> wrote: > I went through a Master/Slave -> High Replication migration over the > weekend and it didn't go well. Hoping I can get some info on if we did > anything wrong but mostly wanted to relay the experience for others. > > I did a couple of test migrations the week before, running the migration > tool through to the end and reverting at the last "create alias" step. I > also ran through the process in its entirety with our staging and build > environments. It always ran smoothly.... > > (Note the use of the ellipsis above. It's what legitimate journalists > refer to as "foreshadowing". Or possibly "foreboding".) > > First hurdle: When it came time to start the migration, the Datastore > Admin tool didn't appear in the console for the destination. Normally, I'm > used to it not showing up in Chrome but this time, it was blank in Firefox > too. IE showed a generic HTTP error page. I needed it so I could clear out > the data from the destination leftover from previous migration tests. I had > already deployed the same version of the app that was currently in the > Master/Slave version. > > Eventually, I looked at the source of the admin console and found the URL > for the iframe it used and launched it directly in Firefox. It was confused > which of the three active Google accounts I regular use should be logged in > so I chose the correct one and carried on, deleting the existing data. > > Next, I launched the migration tool. It hung on the Copy phase (the second > step). I let it go for about half an hour. (During my trial runs, it took > less than ten minutes.) > > So I reverted and went back to the Datastore Admin tool (which now > appeared properly in the Admin Console, at least in Firefox) and deleted > all the data. I went to the Datastore Viewer to verify and could not access > it. I received a 500 Server Error with a link to report the error on this > group. (Incidentally, I am not a big > fan<http://codebetter.com/kylebaley/2011/04/25/google-ui-faux-pas-or-how-to-show-love-hillbilly-style>of > the new Google Groups, especially for AppEngine which has three to > choose from) > > I relied on the Datastore Admin tool to tell me that the data had been > cleared and tried the migration again. Once again, it hung on the copy > phase, this time for almost an hour before I reverted. While it was doing > its thing, I checked the Datastore Admin tool on the destination and almost > from the start, it showed entity totals that were *almost* as high as the > source. But they didn't move during the entire time I waited. I suspect it > was reporting on old data. > > After reverting, I gave up on the migration tool. Before starting the > whole process, I had done the following: > - Switched the source app to a maintenance version that redirects all > traffic to a maintenance page (and if a user is already running the app, > the page is refreshed to show the maintenance page). > - Backed up the data > > So I restored the backup to the HR app and all seems to be running > smoothly on it. The source doesn't have an alias to the new app but I > didn't intend to use one anyway. > > That's my migration experience. The app is up and running now and we just > barely did it under our budget thanks to all the database reads and writes. > An app that normally costs us about ten cents a day cost us almost $4.00 > last night. > > In summary, the major parts I'm not happy with: > - Datastore Admin page not showing up in any browser > - The migration tool apparently not working. (There's a chance it was > actually doing something and I reverted prematurely but my earlier test > runs suggest something went wrong.) > - 500 Server Error on the destination's Datastore Viewer. Furthermore, it > seems unprofessional to direct support to a Google Group for a paid > application. > > The 40x cost increase for the migration I'm okay with. Four dollars still > isn't a lot of money. That said, I'm not sure what I would have done had we > reached our budget. I'm not the billing administrator for either app. > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine for Java" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/google-appengine-java/-/VsiiGEA26eAJ. > To post to this group, send email to > google-appengine-java@googlegroups.com. > To unsubscribe from this group, send email to > google-appengine-java+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/google-appengine-java?hl=en. > -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
