SharePoint Index Partition Degradation

It's been YEARS since I've posted.  I'm still doing the SharePoint thing, but I have a slightly differently role now, and I thought this would be the best place for me to document different issues and resolutions I come across.  I have crossed over into the SharePoint Administrator role.  I'm excited about this and I'm learning a ton.

My first post in this new role is going to discuss SharePoint Index Partition Degradation.  I'm currently trying to get usage reports fully functioning in SharePoint 2013 (look for an additional post on that).  In our test environment I got the ever helpful "Something went wrong" error.  Thanks, Microsoft? :-)  After much research, I determined my error was due to a Search issue.  Search has quit function in our test environment.  I remembered hearing rumblings about that recently and how they kept having to re-index.  Upon further investigation, we have index partition degradation again.  How did I discover this...

First I went to Central Administration/System Settings/Manage Services on Server and located my Search Service.  I noticed it was still running so I clicked on it and then went to the Search Service the Index Partition was showing "0" with a warning triangle.

Then I ran the following PowerShell script:

$ssa = Get-SPEnterpriseSearchServiceApplication

Get-SPEnterpriseSearchStatus -SearchApplication $ssa –Text

My results: 

Confirmation that the partition is Degraded.

There are a couple of solutions to fix the index partition, but I had to know WHY it kept happening.  I stumbled across this https://social.technet.microsoft.com/Forums/sharepoint/en-US/084c736e-75de-4538-8927-7d83362c0b8f/indexing-component-status-is-degraded-sharepoint-2013?forum=sharepointadmin....  SPACE!  A space issue.  My test server is showing this:

We can continue to re-index and run the search manually, periodically, or we could remove the bad partition and create a new using the following script: (found on this site:  http://sharepoint.stackexchange.com/questions/88697/how-do-i-fix-a-degraded-sharepoint-2013-index-partition-when-there-is-only-one-o )

The issue is, re-indexing or creating a new partition is not fixing the root cause of the problem.  I suspect, the only way to fix this is to increase the space on the server.  Our team is planning to rebuild our test environment as part of a separate initiative next week, so for now, we let this sit.  Our environment will be closely monitored for space after the rebuild and if this problem resurfaces, we will go do the path of acquiring more space....stay tuned.