Multiple versions of Solr nodes in the same cloud

[Kudrettin Güleryüz <ku...@gmail.com>]

Hi,

Can I run let's say, Solr 8.5.0 together with Solr 7.3.1. nodes while
replacing older nodes with 8.5.0 one by one?

We have a cloud with rather large disk space utilization. What is the
suggested way to handle this kind of situation? Building indexes takes
around 3 days to complete.

Re: Multiple versions of Solr nodes in the same cloud

[Shawn Heisey <ap...@elyograg.org>]

On 4/6/2020 11:13 AM, Kudrettin Güleryüz wrote:
> Can I run let's say, Solr 8.5.0 together with Solr 7.3.1. nodes while
> replacing older nodes with 8.5.0 one by one?
> 
> We have a cloud with rather large disk space utilization. What is the
> suggested way to handle this kind of situation? Building indexes takes
> around 3 days to complete.

I'm assuming you're running in SolrCloud mode, which is what you get 
when you combine Solr with ZooKeeper.  If that is not the case, then 
what I am saying below will not apply.

Running different major versions in the same cluster would not be 
recommended.  I cannot say whether the later version will write ZK 
information in a way that the older version cannot deal with ... but 
that is always possible.

A rolling upgrade might work perfectly, but it's not a chance I would be 
willing to take when upgrading to a new major version.  Upgrading to a 
new minor version within the same major version would be safer, but also 
not guaranteed.

What I would recommend is that you build a separate cluster with the 
newer version and build new collections in that cluster.  You can run 
them in parallel as long as necessary.  If you like, the new cluster can 
use the same ZK ensemble as the old one, by using a different chroot on 
the ZKHOST string.  You're likely to need more hardware for this 
approach than you would for a rolling upgrade.

Thanks,
Shawn