I am also occassionally seeing the write.lock error message and while trying
to index sometimes Norconex Committer is unable to write to the /data/index
folder, giving error about not able to write to the files in the folder.
This all started happenning since past few weeks and I wonder if all these
issues are related and
whether the permissions of the Solr Service account got changed that may
have caused these issues to all of sudden start to appear.