The low disk space alert is a feature, first introduced in v8.5, that is intended to prevent index corruption due to lack of free space. The warning triggers on the basis of an algorithm comparing the size of your X1 index to available space on your hard drive. We expect the alert to display if the available disk space is 1GB or less than twice the size of the largest set of index files for any one connector (e.g. Email, Files, etc.). The reason for this is that when X1 performs an index merge, the merge operation requires additional disc space (nearly 2 times the size of the index).
You can get an approximation on the size of your indexes by looking at the size of the X1 Search data directory. The X1 Search data directory is found in this pathway by default:
Note: "username" would be your username folder on that computer.
Once there, do a right click on the X1 Search folder and click on Properties. A window will show up and tell you the size of the data. You would need at least double the amount of space freed up or available for the alert to go away.
The best solutions would be to free up additional space, or limit the size of the indices by limiting the amount of data you are indexing to the most critical sources and data stores. Also, check to see if you have enabled 'Store Outlook email body in index", located in Menu>Data Sources>Outlook>gear icon. If you have a local OST file, you do not need to have this setting and it takes up a significant amount of index space.
Lastly, it is possible to move the X1 index to a different location. You may see performance improvements if you move the index to a drive with higher bandwidth. This may include a separate volume or an external drive. We do not recommend moving the index to a network share due to the unpredictability of bandwidth available to network resources.
To move the index storage location as recommended above, go to Main Menu > Options > Indexing > under Storage Locations click on CHANGE LOCATION... > Navigate and click on the directory you would like the storage to be kept > Click OK > Click on Apply Changes.
Lastly, just copying, moving the index and pointing the installation to the new location will not work.