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From Koen De Groote <>
Subject Re: How to prevent solr from deleting cores when getting an empty config from zookeeper
Date Fri, 12 Apr 2019 00:44:51 GMT
I gathered a solr log from 7.6.0 at TRACE level.

Then I replicated the experiment with 6.6.5 and with that version, the
directories were not deleted. Log also included.

The audit log is from solr7. The deletes start at 01:51:48, which
translates to 23:51:48 UTC, which you'll be able to find in the solr7 log.
The directories were deleted, you can see the calls in the audit logs, but
I can't identify in the solr7 log if a delete is being called somewhere.
Could be that it's not logged at all.

I zipped it all and put it on dropbox:

The order of the setup is:

- zookeeper
- solr
- after setup(contains audit log output of a previous attempt)

Anyone trying to replicate, beware to not blindly copy the commands.
This was done on a fresh Ubuntu 18.04 VM, which I suggest for anyone
wanting to test this.


On Thu, Apr 11, 2019 at 11:21 PM Shawn Heisey <> wrote:

> On 4/11/2019 2:40 PM, Koen De Groote wrote:
> > That being explained, am I right in understanding that currently there is
> > no way of configuring Solr so that it won't delete the folders, in this
> > event?
> In my opinion, Solr should never delete cores unless it has been
> explicitly *ASKED* to do so with some kind of delete request.
> I found this issue, which might explain it:
> I think I understand what the goal was with that issue, but if I
> understand it correctly, it basically will cause SolrCloud to delete any
> core from disk on startup which is not referenced in ZooKeeper.
> Can you share a solr.log file from a Solr instance that is deleting
> data?  You'll need to use a file sharing site -- attachments are almost
> always stripped by the mailing list software.  It will be helpful to
> know what directories and core names were deleted, so that info can be
> checked in the log.
> I do not know whether Solr logs anything when it deletes a core.  If
> not, it should.
> Here what I think should happen instead:  If a core that SolrCloud finds
> during startup is not in the ZooKeeper database, it should simply not
> start, with a helpful message at WARN in the log.  The data should never
> be deleted automatically on startup.
> Thanks,
> Shawn

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