1. Why We Exclude Certain Files and Folders
- System files that would, in the event of loss, be best restored from the installation CD/DVD.
- Files holding temporary or transient data which cannot be restored in a meaningful or useful state.
- Files that are themselves backups of data.
- Files holding copyrighted material.
- Files held open by another application.
- Files which cannot be restored due to operating system restrictions.
2. List of Excluded Files and Folders
2.1. Windows
- Browser caches - temporary internet files from e.g. Internet Explorer or Firefox.
- Some other temporary folders, such as
C:\temp. - Backups, such as NTBackup
bkfand ARCservectffiles. - MS SQL database files - please see our MS Exchange and SQL page if you wish to back these up.
- BBC iPlayer downloads.
- The Recycle Bin.
- Virtual machines.
- Suspected 'infected' files quarantined by Sophos.
- Outlook cache files (
*.ost).
- The system files in
C:\WINDOWS. - The system files in
C:\WINNT. - The system files in
*:\Program Files - The system files in
*:\Program Files (x86) - The Office install files in
*:\MSOCache - Cache and generated files in
- *:\...\All Users\Application Data\Microsoft\Search
- *:\...\All Users\Application Data\Microsoft Help
- *:\...\All Users\Application Data\Microsoft\HelpLibrary
- *:\...\All Users\Application Data\Microsoft\Windows Defender
- *:\...\All Users\Application Data\Apple Computer\Installer Cache
- *:\...\All Users\Application Data\Apple\Installer Cache
- *:\ProgramData\Application Data\Microsoft\Search
- *:\ProgramData\Application Data\Microsoft Help
- *:\ProgramData\Application Data\Microsoft\HelpLibrary
- *:\ProgramData\Application Data\Microsoft\Windows Defender
- *:\ProgramData\Application Data\Apple Computer\Installer Cache
- *:\ProgramData\Application Data\Apple\Installer Cache
- *:\...\Application Data\...\Cache
- The TSM installation files in
C:\tsm_images,*:\...\tsm-*-win64.exeand*:\...\tsm-*-win32.exe - The following system files:
- System Object (Windows XP)
- System Services (Windows 2003/Vista)
- Background Intelligent Transfer Service (BITS)
- Event logs
- Removable Storage Management Database (RSM)
- Cluster Database (cluster node only)
- Remote Storage Service
- Terminal Server Licensing
- Windows Management Instrumentation (WMI)
- Internet Information Services (IIS) metabase
- Dynamic Host Configuration Protocol (DHCP)
- Windows Internet Name Service (WINS)
- System State (Windows 2003/Vista/7/2008)
- ASR - Automated System Recovery
These system files are excluded from backup because, in the event of system failure, they can only be restored to identical hardware (make, model, firmware, hardware and configuration). A restore to dissimilar hardware is not supported by Microsoft, as documented in their Knowledge Base.
After a system failure, we recommend that Windows operating system files are always restored using the original Windows media, or the Recovery/Restore CD/DVD that accompanies your machine.
2.2. Mac
- Browser caches - temporary internet files from e.g. Safari or Firefox.
- Some other temporary folders, such as
/private/tmp. - Backups, such as Time Machine.
- BBC iPlayer downloads.
- The Trash folder.
- Virtual machines.
- /Desktop DB
- /Desktop DF
- /Applications
- /System
- /Network
- /bin
- /cores
- /dev
- /usr
- /sbin
- /net
- /etc
- /private (except various log files)
- /tmp
- /Users/.../Downloads/Tivoli Storage Manager*.mpkg
- /.* (all folder starting . on the root of the boot drive)
- All of /Library except the few folders known to contain configuration type information
2.3. UNIX/Linux
3. If You Need to Back Up Excluded Files...
If you need to back up any of the files listed above, this may still be possible. Some of these exclusions are negotiable, so if you feel you have good reason for having some of these files included in your backup, please contact hfs@ox.ac.uk with details.

