Exploring the SETI@home Directory: What Files and Folders Mean

Recent Trends: The Project’s Shift to Hibernation

SETI@home, the volunteer computing project searching for extraterrestrial intelligence, paused new workunit distribution in March 2020. Since then, the software and its local data directory have remained largely unchanged for millions of participants. Current discussions among users focus on understanding what each file in the SETI@home directory represents, especially as they consider deleting or archiving their data.

Background: Standard Directory Structure

When a user installs the BOINC client and attaches to SETI@home, the software creates a dedicated folder (typically SETI@home inside the BOINC data directory). The following core files and folders are generated:

• slots/ – Contains workunit-specific subdirectories (slot_X). Each slot holds the executable and temporary data for a running or cached task.
• projects/ – Holds project files including the science application, graphics libraries, and configuration data.
• results/ – Stores completed workunit results (e.g., out files) that were uploaded to the server.
• state.xml (or client_state.xml at the BOINC level) – Tracks the current state of attached projects and tasks.
• workunit_*.sah – Individual workunit files—binary files containing radio telescope data chunks for processing.
• *.log – Log files showing task execution messages, error reports, and communication with SETI@home servers.

User Concerns: What to Keep and What to Remove

With no new workunits arriving, many volunteers wonder which files are safe to delete without losing their contribution history or credits. Key considerations include:

• Account credits – Your total credit count is stored on the SETI@home server, not in local files. Deleting local data does not erase your contribution history.
• Workunit files – Completed .sah files are no longer needed by the project; they can be removed to free disk space.
• Results and log files – These are sent to the server upon completion. Stale logs are safe to delete.
• The “slots” folder – If you no longer intend to run SETI@home tasks, this folder can be cleared. Its contents are ephemeral.
• Personal scientific interest – Some users retain raw data to examine signal patterns offline. This is allowed, but the data is proprietary to the project.

Likely Impact: Preserving Data vs. Moving On

The immediate impact of understanding the directory structure is two-fold: (1) users can reclaim significant disk space—often several gigabytes per year of participation—and (2) they can decide whether to keep data for potential future analysis if SETI@home resumes or releases its database for public research. The project has stated that no new data collection is ongoing, but the existing archive remains housed at the University of California, Berkeley. Local copies have no further functional value to the project itself.

What to Watch Next

Looking ahead, a few developments could affect how the SETI@home directory is used:

• Project revival or data release – If SETI@home announces a transition to a citizen‑science archive, volunteers who kept their old data might contribute to validation or machine learning studies.
• BOINC platform updates – Future BOINC clients may change how project directories are structured, potentially archiving or converting legacy data automatically.
• Community archival efforts – Independent groups have created tools to extract and visualize workunit data. Monitoring these projects could guide users on which folders to preserve and which conversion tools are reliable.
• Storage optimization guides – As more users clean up their BOINC installations, step-by-step tutorials for safely pruning the SETI@home directory without harming other BOINC projects are likely to become more common.

For now, analyzing what each file and folder means remains a practical first step for any user deciding the fate of their local SETI@home data.