Backup and Backup Copy synthetic operations such as retention (merging) or Synthetic Full creation on ReFS based repositories could lead to following issues:
- Memory exhaustion on Repository Servers with ReFS
- Synthetic operations take a considerable amount of time
- The Repository server becomes unresponsive or has significantly reduced performance
As described in Microsoft article KB4016173 the root cause resides in the existing design of ReFS metadata management.
After performing many tests across multiple installations, our RnD and Solution Architects have found the below recommendations to be most effective for resolving the symptoms described in the "Challenge" section:
Use the following OS versions to avoid any known ReFS issues described in “Challenge” section:
- Windows Server 2019 (not officially supported until Veeam Backup and Replication 9.5 Update 4. Lab use only)
- Windows Server 2016 patched to at least September 2018 updates (KB4343884 or later)
- Windows 10 Pro for Workstations
Veeam and Microsoft recommend keeping all systems fully updated with the most recent Windows Updates for best performance.
Backup repository should meet minimum system requirements. In particular:
- CPU: at least 1 core per each concurrent backup proxy task and at least 1 core for each two concurrent repository tasks recommended
- RAM: Backup repository server running other backup roles should have an appropriate amount of RAM for each role
- Storage: 64K ReFS volume formatting is recommended
Uninstall the following 3rd party software that have been reported to cause ReFS stability and/or performance issues:
3rd Party Software
- Antivirus software (except Windows Defender)
- Microsoft Configuration Manager Client
Please be aware that we’re making changes which will restrict access to product updates for users without an active contract.