DiskImages

DiskImages is a term used to describe files or devices that contain a complete copy of a storage medium, including all sectors, the partition table, the filesystem metadata, and user data. A disk image aims to reproduce the exact structure of the source device, rather than just the files it contains. Disk images can be created from whole drives or individual partitions and may be stored in various container formats. They are used for backup and archival, software distribution, virtualization, and forensic preservation.

Common formats and characteristics vary by use case. ISO images typically contain optical disc data ready for mounting or burning. RAW or IMG formats store sector-for-sector copies. Disk images may be compressed or uncompressed, and some formats support features such as sparse representation or encryption. Virtualization environments frequently use VHD/VHDX (Microsoft Hyper-V), VMDK (VMware), or QCOW2 (QEMU/KVM). macOS commonly uses DMG images for distribution and backup. The choice of format affects compatibility with tools and hypervisors, as well as performance and storage efficiency.

Creation and manipulation of disk images are supported by a range of tools. Low-level tools such as dd and ddrescue perform direct sector imaging, while higher-level utilities like Clonezilla, Macrium Reflect, and commercial backup suites provide guided workflows. Platform-specific tools include Disk Utility on macOS and various imaging programs on Windows. Image files may be mounted to access their contents without restoring, or attached to virtual machines to boot an environment directly from the image.

Access, integrity, and portability are important considerations. Images can be mounted or attached to systems for use, and their integrity is commonly verified with cryptographic checksums. Limitations include potential licensing restrictions, incompatibilities with hardware or hypervisor targets, and the need for sufficient storage capacity.