Are you trying to run Solr on a Windows 7 machine and running into issues? Unfortunately, this is somewhat expected due to lack of testing and reports of limited successes.
Although reported with limited success, a Solr installation on a Windows 7 machine has not been fully tested. Per our system requirements, we recommend having Windows Server 2008R2 or Windows Server 2012.
This can be referenced under “Solr Search Requirements“ - http://www.ektron.com/Documentation/System-Requirements/
Also, the rule of thumb for hard drive space is 3 to 5 times the size of the site. The size of the site should be calculated as:
Database + Assets + Estimated Growth (over 2-5 years)
Three big reasons:
1. The search engine ingests and stores all searchable content and associated metadata within the site’s database and assets
2. Searchable assets are transferred to (and cached on) the search server so that they can be indexed
3. Some specialized index fields duplicate content in support of various language and processing features.
The search engine maintains metadata on top of the indexed content to optimize the querying process.