Solr Shards down for unknown reason

[Dasarathi Minjur <ze...@gmail.com>]

We have a Hadoop cluster with Solr 6.3 running as service. After an OS
security patching, when the cluster was restarted, Solr Cloud is up but the
shards are down all the time. No specific messages in Solr.log or console
logs. Tried restarting solr but that didn't help. Any pointers to get the
shards up will be helpful. Thanks for taking time to respond.

Re: Solr Shards down for unknown reason

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

On 10/15/2018 1:30 PM, Dasarathi Minjur wrote:
> We have a Hadoop cluster with Solr 6.3 running as service. After an OS 
> security patching, when the cluster was restarted, Solr Cloud is up 
> but the shards are down all the time. No specific messages in Solr.log 
> or console logs. Tried restarting solr but that didn't help. Any 
> pointers to get the shards up will be helpful. Thanks for taking time 
> to respond.

Not having anything show up in the log is worrying. Normally if things 
don't come up, at least one of the nodes in the cloud should log 
SOMETHING to indicate what went wrong.  But given the age of the version 
you're running, I'm not really surprised by ANY strange behavior.

6.3.0 was released two years ago - which is a LONG time in open source.  
Solr has a more aggressive release pace than a lot of other software 
packages.  There are eleven 6.x releases after 6.3.0, and twenty total 
releases after 6.3.0 if you count 7.x as well.  The 6.x line in 
particular had a very large number of SolrCloud-related bugfixes and 
improvements, with major focus on stability.

Version 6.3 won't see any fixes.  Even 6.6.x, which is the only branch 
in 6.x that will EVER see any fixes, is only going to get really major 
updates, particularly security bugs.

All that goes to say ... you might have to upgrade Solr to even 
troubleshoot the problem, if 6.3.0 logs nothing.  If a problem is found, 
you'll definitely have to upgrade to get a fix, unless you're willing to 
patch and build the 6.3.0 version yourself.

Thanks,
Shawn