Supported operating systems
| Operating system | Professional Edition | Server Edition |
|---|---|---|
| Windows 11 | yes | yes |
| Windows 10 | yes | yes | Windows Server 2012 | no | yes* |
| Windows Server 2012 R2 | no | yes* |
| Windows Server 2016 | no | yes* |
| Windows Server 2019 | no | yes* |
| Windows Server 2022 | nein | ja* |
| Windows Server 2025 | nein | ja* |
* All variants of this server operating system are supported, except Core-Installations
If you wish to use the network functionality, you must also have the following available:
Access permissions
You need local administrator permissions for the installation and for its later use. This is usually the case, if you were able to install other programs before.
In a network, you must be the domain administrator if you wish to install and control O&O Defrag locally as well as on the network computers.
Microsoft Windows Installer
The installation takes place with the help of the Microsoft Windows Installer. It is a Windows integrated component which controls all installation and uninstallation.
O&O Defrag supports all Windows file systems. The following paragraphs will tell you more about each of these file systems.
| File System | Explanation |
| exFAT | Starting from Windows Vista, the exFAT-file system is supported. This was designed especially by Microsoft in regard to flash drives, and delivers better performance than FAT. It is also much better against structural damage to the file system and protected against data loss. |
| FAT | FAT is the oldest data system, the roots of which go back to MS DOS. It is supported by Windows. O&O Defrag can be used without any problem on FAT drives. |
| FAT32 | FAT32 is the native file system of Windows 95b/98/Me. It offers some advantages compared to the older FAT. FAT32 drives are Windows- supported by default and can be defragmented without any problem using O&O Defrag. |
| NTFS | The NT file system was developed completely new for the Windows NT family. It offers the option of security restrictions on the file level, increases the security against data errors, and achieves higher performance.It is supported by Windows. And O&O Defrag gets optimal results when defragmenting NTFS drives. |
| EFS | A file system introduced with Windows 2000 which is based on NTFS and its encryption ensures higher data security against abuse or unauthorized access. The Encrypted File System (EFS) makes data for unauthorized users unreadable. O&O Defrag supports EFS hard disks; neither data integrity nor data security is compromized. |
Supported hardware
O&O Defrag supports all hardware components that are supported by Windows. Please note the software requirements of the corresponding manufacturer.
As a rule: if you can access your hardware with Windows as you would a normal Windows partition, and this partition is formatted using a supported file system, this hardware can be defragmented. Removable drives such as streamers or CD-RWs are exceptions, since defragmenting them might not be useful. You can also set network drives as target for defragmentation.
RAID
Striped-, Mirrored- and RAID5-Volumes: The advantage of these drive types lies in their superior speed, which on the one side facilitates accessing and storing processes, and on the other hand offer a higher degree of data security.
O&O Defrag supports all known RAID systems. According to many hardware manufacturers, defragmenting RAID systems is especially important: as their files are spread over several hard disks, their fragmentation level is likely to be very high.
