Sparse Files Were Skipped (code 1551)

Situation

A backup plan completed with the following warning message: Sparse files were skipped: Backup of Sparse files is not supported.

Cause

Sparse files are files that contain large regions of empty or unallocated data. Instead of storing these empty regions on disk, the file system records them as gaps, allowing the file to appear much larger than the actual disk space it occupies. Sparse files are commonly used by virtual machine disks, databases, disk images, and applications that allocate large files in advance.

MSP360 Backup does not support backing up sparse files. During a backup, any sparse files that are detected are skipped and are not included in the backup.

How to identify sparse files

Windows: fsutil sparse queryflag Linux: filefrag, stat, or compare the logical size (ls -l) with the actual disk usage (du). macOS: Compare the logical file size with the allocated disk space using ls -l and du.

Solutions

Solution 1

If you need to back up the data contained in a sparse file, convert the file to a regular (non-sparse) file before running the backup.

The conversion method depends on the operating system. In general, you need to create a new file and copy the data in a way that writes all allocated and unallocated regions to disk, producing a regular (non-sparse) file.

Windows

Copy the file with 'fsutil'.

1. Open Command Prompt as an administrator.
2. Check whether the file is sparse:

fsutil sparse queryflag "C:\path\to\file"

C:\path\to\file - use the path to the sparse file

3. Create a regular copy of the file. For example:

copy "C:\path\to\sparse.file" "C:\path\to\regular.file"

4. Verify that the new file is no longer sparse:

fsutil sparse queryflag "C:\path\to\regular.file"

Linux

Use 'cp' with the '--sparse=never' option:

cp --sparse=never sparse.file regular.file

Alternatively, use 'dd':

dd if=sparse.file of=regular.file bs=1M

Verify the result:

ls -ls sparse.file regular.file
du -h sparse.file regular.file

The regular file should occupy approximately its full logical size on disk.

macOS

macOS does not provide a built-in tool specifically for converting sparse files. In most cases, creating a new copy of the file using an application that rewrites its contents produces a regular file. Depending on the file type, you can also use:

cp -c sparse.file regular.file

or

dd if=sparse.file of=regular.file bs=1m

Workaround

Exclude the affected sparse files from the source scope of your backup plan.