---
title: "How Space Wizard Works"
description: "How a scan runs: native du with a Node.js fallback, cloud-folder exclusions, the three-pass SHA-1 duplicate check, and trash-bin safe deletion."
url: "https://royalsoftworks.com/products/space-wizard/how-it-works/"
source: "https://royalsoftworks.com"
format: "markdown"
note: "Markdown rendering of the HTML page at `url`. Same content, same canonical URL."
---

How it works

# A scan, a breakdown, a cleanup. In that order.

No background service, no daemon, no scheduled job. A scan runs when you ask for one, against the drive — or the server — you point it at.

From click to cleanup

## What happens when you scan a drive.

1. 01

   ### Pick a source

   A local drive, or a saved remote host. Free scans your home drive; Pro opens every local drive on the machine. Remote hosts work on either tier.
2. 02

   ### Cloud-sync folders are skipped

   OneDrive, Dropbox, iCloud, Google Drive, Box, pCloud and MEGA are excluded by default — their placeholder files aren't real local bytes, and walking them can make the provider download the real thing. One switch includes them if you want.
3. 03

   ### The walk runs, 64 folders at a time

   Locally, a concurrent breadth-first walk reads up to 64 directories at once and reports each folder's direct size as it goes, so the running total climbs while the scan is still working. Junctions and symlinks are resolved so nothing is counted twice.
4. 04

   ### Nothing is quietly dropped

   Files the kernel refuses to open — pagefile.sys and friends — are sized from the directory entry instead, roughly 15 GB most scanners lose on a system drive. Folders that couldn't be read at all are counted and surfaced, with a one-click restart as Administrator.
5. 05

   ### Remote hosts take the same path, differently

   On a host with a shell, a single \`find\` command streams type, size and path for the whole tree in one pass. Without one — a locked-down SFTP account, or plain FTP — it falls back to a directory walk over as many parallel connections as that host allows.
6. 06

   ### Duplicates get a three-pass check

   Files are grouped by exact byte size; unique sizes are dropped immediately. Survivors get a SHA-1 of their first 4 KB. Only what still matches is hashed in full. Remotely, both hash passes run on the host, so hashes cross the wire rather than files.
7. 07

   ### You see bars or a donut

   The same result renders as a bar chart or a donut of the folder you're standing in — the nine largest children plus an "Other" bucket. Open one and the chart follows you down.
8. 08

   ### Clear what you don't need

   Multi-select in the Duplicates tab or browse the Files tab directly. At least one copy in every duplicate group is always kept. Local deletions go to the recycle bin; remote deletions are permanent, and the button says so.

For your IT team

- **Local walk** — Node.js concurrent breadth-first walk, 64-way, streaming per-directory results in batches; depth capped at 512
- **Remote walk** — GNU \`find -printf\` single stream where available; otherwise a concurrent readdir walk over 1–16 connections (default 5)
- **Duplicate hash** — Exact byte size → SHA-1 over the first 4,096 bytes → full SHA-1 on survivors, 8 files at a time, largest first
- **Remote hashing** — \`dd bs=4096 count=1 | sha1sum\` for the prefix pass and \`sha1sum\` for the full pass, executed on the remote host
- **Deletion** — OS trash / recycle-bin API locally; direct remove over SFTP or FTP on a remote host
- **Licence gate** — Free: home drive only, 100 GB measured per scan. Pro: every local drive, no cap. Remote hosts on both.

## No account. No sync. No telemetry.

Scanning never touches the network. Space Wizard makes exactly two outbound calls in its whole life: checking a licence key when you activate one, and checking for a new version once after launch. Both are optional — there is an offline licence file for machines that never go online at all.

## Pointing it at production?

Host-key verification, credential storage and exactly what a scan touches — before you connect it to anything that matters.

[Security](https://royalsoftworks.com/products/space-wizard/security/) [Read the whitepaper](https://royalsoftworks.com/products/space-wizard/whitepaper/)