Snapshot Comparison

The Snapshot Comparison tool lets you compare two FolderSizes snapshot (.fssx) files and see exactly what's changed between them - folders and files that were added, deleted, or modified, along with the metadata behind each change.

This makes it easy to answer questions like:

• What grew the most on a file server between last month and this month?
• Which folders were created or removed since a known-good baseline?
• Did anyone change attributes, owners, or modification times on a sensitive folder?
• How much disk space was net added or freed during a system change?

Getting Started

To compare two snapshots:

1. Generate a snapshot of your file system at an initial point in time (see Generating Snapshots).
2. At a later time, generate a second snapshot of the same path(s).
3. Open the Snapshot Comparison tool from the FolderSizes ribbon bar.
4. Choose your source snapshot (typically the earlier file) and your target snapshot (the later file), then start the comparison.

FolderSizes imports both snapshots into a temporary working database and performs the comparison. For very large snapshots, an "indexing" step at the end of import prepares the data for efficient drill-down. The whole process can be cancelled cleanly at any stage.

The Comparison Window

Once the comparison is ready, the tool window shows two panes:

• Folder tree (left): the merged folder hierarchy across both snapshots. Each folder is labeled with its state and a size summary that shows how its total contents differ between the source and target.
• Detail report (right): when you select a folder in the tree, the report shows every file and immediate subfolder of that folder, side-by-side. Each row carries a colored "State" pill plus columns for source/target size, modification time, attributes, owner, link target, and creation/access timestamps.

State conventions used throughout the window:

• Added - present only in the target snapshot. Shown with a "+" glyph in the tree and a red pill in the detail report.
• Deleted - present only in the source snapshot. Shown with a "−" glyph and a green pill.
• Modified - present in both snapshots but with at least one difference. Shown with a "*" glyph and an accent-colored pill.
• Unchanged - present in both snapshots with no detectable differences. Shown in a neutral color.

The color convention follows the rest of FolderSizes: red represents growth (target larger or new items) and green represents shrinkage (target smaller or removed items).

Folder Tooltips

Hover over any folder in the tree to see a detailed comparison tooltip. The tooltip shows the folder's full path, its state, a "reason" line explaining why a folder is flagged as modified (its own metadata changed, its aggregate size/count changed, or one of its descendants changed), and side-by-side comparisons of size, file count, folder count, timestamps, attributes, owner, and link target.

This lets you inspect any folder's full set of comparison facts without first having to select it.

Filtering

The toolbar provides four toggle buttons - Added, Deleted, Modified, and Unchanged - for filtering the comparison view by state. All four are enabled by default; click a button to hide items of that state. The pressed/unpressed state of each button shows at a glance which categories are currently visible.

Filters apply to both the folder tree and the detail report. The folder tree uses path preservation: a folder remains visible whenever its own state matches the filter or any descendant matches, so you can always navigate to a filtered-in item through its ancestors.

Some practical examples:

• Uncheck Unchanged to show only the parts of the file system that have changed.
• Uncheck everything except Added to see only new items.
• Uncheck Added and Deleted to focus on in-place modifications.

Drilling Into Details

The detail report shows folder rows in addition to file rows. Double-click any folder row to select that folder in the tree and load its own detail report - a quick way to walk down through changed subtrees without manually expanding the tree node-by-node.

Exporting Results

The toolbar's Export button reveals a menu of formats: CSV, plain text, HTML, and XML. Exports reflect the currently-visible detail rows (with whatever filters you have applied), so you can capture comparison results for distribution or further analysis without losing the focus you've already established.

Tips for Effective Comparison

• Use matching root paths. Comparisons are most meaningful when source and target snapshots cover the same root path(s). If the roots differ, FolderSizes will align them by index and surface a notice.
• Match snapshot scope. If one snapshot uses scan filters and the other doesn't, items excluded by filtering will appear as "added" or "deleted" in the comparison - even though they may not actually have changed on disk.
• Reason line first. When a folder is flagged Modified, check its tooltip's "Reason" line to see whether the change is in the folder's own metadata, its aggregate counts, or in a descendant. This is especially helpful when a deep change has propagated up through many parents.

Related help topics: About Snapshots, Generating Snapshots, Using Snapshots, Comparing Scan Data