The description of gthr format expansion
The gthr file is a text document, which contains system data log, collected by Microsoft logging utility. The file is created with Windows Search, Microsoft Exchange and SharePoint Portal Server after indexing process per each file.
Both Microsoft Exchange and SharePoint Portal Server generate GTHR-files for the identification of the document and messages, which were not indexed successfully. They can be viewed with Gthrlog.vbs utility.
As far as GTHR-files contain only index data, they can be deleted, if they reach too large size. Next time after the indexing process launch in Windows the routine processing can take quite longer period of time.