Hi folks!
I run a solrcloud deployment and we're about to start the v7->v8
upgrade. It's large enough that building fully parallel infra isn't
palatable so we were looking at mixed / in place upgrades.
From my initial reading I have a few questions I was hoping y'all could
help with:
1. The upgrade process[1] suggests an N+/-1 compat story, e.g. 8.11.2
should be able to co-mingle with 7.>3 but I haven't turned up any firm
statements about that.
2. Is there forward/backward compatibility between segment/index files
between version? e.g. we have automatic core recovery from backups in
the event that a node fails. If I'm running a v8 node that fails after a
backup has been taken and the core gets restored to a v7 does that sound
problematic? (I'm guessing maybe/yes per [3])
3. the docs refer to IndexUpgraderTool[2] but nothing indicates when/if
I should be running this manually as far as I can tell. How does this
come into play?
And of course if there are any docs it sounds like I may have missed (or
useful threads / issues / whatever) comes to mind that I should read
feel free to point me at them.
Thanks so much!
-richard
[1]: https://solr.apache.org/guide/8_7/upgrading-a-solr-cluster.html
[2]: https://solr.apache.org/guide/8_7/indexupgrader-tool.html
[3]:
https://cwiki.apache.org/confluence/display/LUCENE/BackwardsCompatibility#BackwardsCompatibility-FileFormats
