What is 'Other Volumes in Container'? (And Why It's So Large)

You opened Disk Utility, saw "Other Volumes in Container" taking up a lot of space, and started worrying. It looks like something is wrong. It's not.

This is just how APFS (Apple File System) reports storage. Let us explain what's actually happening.

APFS 101: Containers and Volumes

Before 2017, Mac hard drives used HFS+. Each partition was a fixed chunk of disk space. If one partition filled up, it couldn't borrow space from its neighbor.

With APFS, Apple introduced Containers. A Container is a single pool of storage where multiple Volumes live. All volumes share the same space dynamically.

This is actually better for most users. But it makes storage reporting confusing.

What's in "Other Volumes"?

The "Other Volumes in Container" category typically includes:

1. System Volume
The read-only part of macOS that runs your computer. Usually around 15GB.

2. Data Volume
Where your files actually live. This is what you normally interact with.

3. Preboot
Boot configuration files. Small, a few hundred MB.

4. Recovery
The emergency recovery system. About 1GB.

5. VM (Virtual Memory)
Swap space used when your RAM is full. Can grow significantly if you never restart.

6. APFS Snapshots
This is often the main culprit. Snapshots are "frozen" copies of your disk created by Time Machine or during macOS updates.

Why Snapshots Make It Look Bigger

Here's what confuses people: even if you delete a large file, the space might not free up immediately. Why? Because a snapshot still contains that file.

Snapshots are designed to expire over time, but "over time" can mean days or weeks.

How to check for snapshots:

tmutil listlocalsnapshots /

If you see many snapshots from days or weeks ago, they might be holding onto deleted data.

How to delete specific snapshots:

sudo tmutil deletelocalsnapshots 2025-10-08-143022

Replace the date with an actual snapshot name from the list.

Simple Fixes That Often Help

1. Restart your Mac
This clears VM swap files. If you haven't restarted in weeks, swap files could be taking significant space.

2. Delete old snapshots
Use the tmutil commands above to remove snapshots you no longer need.

3. Wait
Sometimes APFS needs time to reclaim space after deletions. If you just cleaned up a lot of files, check again in a few hours.

What DissectMac Shows

Disk Utility shows container-level information, which isn't always actionable. You can't click "Other Volumes in Container" and see which files are the problem.

DissectMac scans your actual Data volume—the part you can control. It shows which folders in ~/Library and elsewhere are taking space. That's usually more useful than staring at Disk Utility's container breakdown.

Pro Tip

If storage looks weird right after a macOS update, give it 24 hours. The system is often re-indexing Spotlight, rebuilding caches, and cleaning up installation files. The space situation often improves on its own.

See What's Actually Using Space →