How to test the migration from 2.x to 3.x?


#1

I’m preparing to migrate from latest Nexus 2.x running on one machine to latest Nexus 3.x running on a new machine and am looking for advice on how to test this migration before actually performing it.

I will be following the instructions documented here:
https://help.sonatype.com/repomanager3/upgrading/upgrade-procedures

From reading this it’s not clear if I can run the migration multiple times using the “download” method? ( I know I’ll have to wipe the 3.x instance before doing it again) or does running the migration change anything on the Nexus 2.x system which would need to be rolled back or that I should be concerned with?

Any feedback would be appreciated.

Thanks!


#2

Hey Josh,

Nothing is changed from on Nexus 2 instance so the only “roll back” is deleting your Nexus 3. The NX2 remains running during the migration. The only down time would be when you are switching over.

The download method is by far the slowest as it makes a copy of the data through http. You might want to consider the hard-linking method or even network copy if possible. Nether one effect your NX2 instance as well.


#3

@josh.behrends In some cases, you may also need to clear up the migration data from Nexus 2 and restart. See Upgrade Procedures for more info.


#4

Out of curiosity what is stored in “$data-dir/db/migrationagent”? and how is it used? Just wanted to understand what I’m deleting.

Thx!


#5

@josh.behrends When you start a migration, NXRM 2 itemizes all of the components that will need migrating in a sort of to-do list for the migration agent. Then (since migration can take a while) it also logs any changes (deletions, later additions) to that to-do list, so NXRM 3 will catch those as well. That’s stored in the ‘migrationagent’ db. None of it is authoritative data for NXRM 2; if you start migration again, that database will be re-created.