Does 7-Zip Support Multi-Volume Solid Archives?

7-Zip does not natively support creating multi-volume solid archives in a single step through its standard compression menu. When you configure an archive to split into volumes within 7-Zip, the software automatically disables solid compression and switches to non-solid mode. However, users can still achieve a multi-volume solid archive by utilizing a simple two-step workaround using 7-Zip's built-in file splitting tools.

The Native Behavior of 7-Zip

When creating an archive in the .7z format, solid compression combines multiple files into a single continuous data stream before applying the compression algorithm. This significantly improves compression ratios, especially when archiving large numbers of similar files.

If you specify a volume size in the Split to volumes, bytes field inside the "Add to Archive" dialog, 7-Zip automatically turns off solid compression. Each file is compressed independently within the boundaries of each volume.

The developer designed it this way for practical reliability reasons:

  • Error Recovery: In a true solid archive, damage to one volume corrupts the entire continuous data stream, making it impossible to extract files located after the damaged block.
  • Extraction Performance: Extracting a single file from a middle or late volume of a solid archive requires decompressing all preceding volumes from the beginning.

Workaround: How to Create a Multi-Volume Solid Archive

If maximizing compression is your priority and you still require split files (for example, to fit specific storage media or bypass file upload limits), you can create a multi-volume solid archive using a two-step process:

Step 1: Create a Single Solid Archive

  1. Select the files or folders you want to compress.
  2. Right-click the selection and choose 7-Zip > Add to archive....
  3. Choose the 7z archive format.
  4. Set the Solid Block size to your preferred setting (such as Solid).
  5. Leave the Split to volumes, bytes field completely empty.
  6. Click OK to generate the solid .7z file.

Step 2: Split the Solid Archive

  1. Locate the newly created .7z file.
  2. Right-click the file and select 7-Zip > Split file....
  3. In the dialog, select or type your desired volume size.
  4. Click OK.

7-Zip will split the single solid archive into raw segments with extensions like .7z.001, .7z.002, and .7z.003.

How to Extract Split Solid Archives

To extract the files later:

  1. Ensure all split parts (.7z.001, .7z.002, etc.) reside in the exact same directory.
  2. Right-click only the first file (.7z.001).
  3. Select 7-Zip > Extract Here or Extract to....

7-Zip automatically detects all subsequent volumes, reconstructs the solid stream in memory, and extracts the contents.