Challenge
Backup job retention processing on ReFS-based backup repositories leads to following issues:
- Repository server becomes unresponsive or crashes.
- I/O performance on the server is reduced significantly.
- The server experiences high memory usage.
Cause
As described in Microsoft article KB4016173 the root cause resides in the ReFS metadata management logic of the Windows OS system memory manager.
Solution
Operating System
Use the following OS versions, which include fixes to the ReFS metadata management logic:
- Windows Server 2019 (requires Veeam Backup and Replication 9.5 Update 4 or later)
- Windows Server 2016 patched to at least September 2018 updates (KB4343884 or later)
- Windows 10 Pro for Workstations
Note: refs.sys driver version should be at least 10.0.14393.2457 or later. However, for best performance and security, we always recommend keeping all systems fully patched with the most recent Windows Updates .
Hardware
Backup repository must meet minimum system requirements. In particular, pay attention to the following in case of all-in-one backup appliances:
- CPU: ensure at least 1 core per each concurrent backup proxy task AND at least 1 core for each two concurrent repository tasks are available.
- RAM: ensure the repository server has enough RAM (at least the sum of RAM requirements for each individual Veeam component installed on the server).
- Storage: use 64KB cluster size when formatting the ReFS volume.
3rd Party Software
Uninstall the following 3rd party software that have been reported to cause ReFS stability and/or performance issues:
- Antivirus software (except Windows Defender)
- Microsoft Configuration Manager Client