Backup Options
Backup options control how O&O DiskImage stores data, how much space it uses, whether the result is checked, and how long old backup runs are kept.
Backup Strategy
| Strategy | What it does | Best for |
|---|---|---|
| Full | Stores all selected data every time. | Standalone archive points and simple retention. |
| Incremental | Creates a full backup first, then stores changes since the last backup run. | Regular automatic protection with efficient storage use. |
| Differential | Stores changes since the last full backup. | Easier chains than incremental, with more storage use. |
Incremental is the default strategy and is usually the best balance of speed and storage. Differential backups can be easier to manage because each differential depends on the full backup rather than the immediately previous change backup. Full backups are simplest but require the most storage.
Execution Policy
The execution policy can create a new full backup after a configured number of change backups. This reduces the risk of very long incremental or differential chains and makes restore points easier to manage over time.
Backup Technology
| Technology | Meaning |
|---|---|
| Used sectors | Backs up only sectors that contain data. This is recommended for normal use. |
| Forensic | Creates a bit-precise copy of the entire source, including empty sectors. |
| Direct forensic | Creates an exact copy directly from the data carrier and is intended for Fortress Mode scenarios. |
Forensic backups require storage close to the full size of the source, not just the used data size.
Backup Format
| Format | Notes |
|---|---|
| O&O DiskImage format | Recommended standard format. Supports all normal backup and restore options. |
| VHD | Microsoft virtual hard disk format. Useful for virtual mounting, with limited O&O DiskImage restore options. |
| VHDX | Newer Microsoft virtual disk format with larger capacity and better virtual disk features. |
When you create VHD or VHDX files, Windows may automatically mount or display them during backup. That is normal and does not affect the backup.
Compression
Compression is enabled by default. The standard Lempel-Ziv option is optimized for performance and is the best general-purpose choice.
Available compression methods include:
- Lempel-Ziv standard: fast, lossless, moderate space savings.
- Lempel-Ziv maximum: stronger compression with more processing time.
- ZIP deflate: efficient for file backups; image backups fall back to Lempel-Ziv standard where required.
- BZIP 1K, 4K, 9K block sizes: increasing compression strength with increasing processing time.
VHD and VHDX backups do not use compression.
Encryption
Enable Encrypt backup with password to protect backup contents from unauthorized access. O&O DiskImage requires the original password when restoring or opening encrypted backups.
Store the password in a password manager or another secure place. O&O DiskImage cannot restore an encrypted backup without it.
Validation
Validation checks the backup file after completion for structural integrity. It adds time to the backup run but is valuable for important backups and new destinations.
Recovery partitions can have special characteristics that may cause validation to fail even when the backup itself is usable. The Skip validation for recovery partitions setting skips validation for backups that contain recovery partitions while leaving the backup unchanged.
Retention Policy
The retention policy defines how many backup runs are kept. When the limit is reached, O&O DiskImage deletes the oldest eligible backup run.
Retention is intentionally cautious with incremental chains. Deleting a backup that later incremental backups depend on would break the chain, so retention may be disabled or limited depending on the strategy.