We want to keep this discussion consumable and on-topic, so before you post your feedback or issues in this thread, please be sure your backup repository meets the following requirements:
Using the following OS versions will ensure you're not running into any known ReFS issues:
• Windows Server 2019 (not officially supported until Update 4, so use it for lab environments only please).
• Windows Server 2016 patched to at least September 2018 updates (KB4343884 or any later one, since Windows Updates are cumulative).
• Windows 10 Pro for Workstations
You can double-check that you're on the right patch level by verifying that your refs.sys driver version is 2457 or later.
Make sure your backup repository server meets minimum system requirements, particularly around:
• CPU: we recommend allocating at least 1 core per each concurrent backup proxy task, and at least 1 core for each two concurrent repository tasks.
• RAM: if the backup repository server is running multiple Veeam roles, please add up memory requirements of each individual role.
• Storage: we recommend formatting the ReFS volume with 64KB block size.
3rd Party Software
Uninstall the following 3rd party software that have been reported to cause ReFS stability and/or performance issues:
• 3rd party antiviruses (but not Windows Defender)
• Microsoft Configuration Manager Client
If possible at all, we recommend that you start troubleshooting ReFS issues from performing a clean installation of an operating system from the original Windows installation ISO from MSDN, to ensure no bloatware is installed along from vendor-provided installation media. Please create the dedicated topics if you'd like to discuss some specific incompatibilities with the specific 3rd party software, and we will update this master post with results of the corresponding discussions.
For more information on what we know so far, I am reposting the snippet of my "Word" section of the Veeam forum digest from a few weeks ago:
Thanks!Gostev wrote:We have now completed the stress testing of ReFS driver version 2457 (released 1 month ago as a part of KB4343884). As a reminder, this was a milestone update that brought the backport of ReFS driver memory management fixes from Windows Server 2019 branch. So we decided to really put this driver through its paces in our stress testing lab to validate those changes. Just in case you're wondering why we tested the original version, and not the most current from the latest Windows update - this is because this sort of stability testing takes a few weeks. But the future driver versions of course include all these changes too, anyway. And long story short, I'm happy to report that ReFS remained stable no matter what challenges we threw at it.
The last stress test was particularly impressive, because it was done on a 40TB ReFS repository with just 8GB RAM in the server – which is our minimum system requirements and way below the current recommendation of 1GB per 1TB. Backup job configuration was also the toughest for ReFS to handle with over a hundred VMs, per-VM backup file chains and weekly synthetic fulls enabled for – meaning, the retention process had to delete hundreds of backup files with the total virtual size of 60TB at once - configuration which pretty much guaranteed server lockups before. But the latest ReFS driver chew through this like a piece of cake, with no spikes for either CPU or RAM and no system freezes – very impressive with just 8GB physical RAM. In fact, top RAM usage was just 5.4GB (metafile maximums were 4.5 GB total and 2.1GB active), while CPU load of the 4 vCPU VM was hovering at around 10%.
Does it mean this is finally the end of the ReFS troubles, at least at a wide scale? Anecdotally, we're already starting to receive such confirmations anyway. For example, one of our solution architects has two identical ReFS repositories in his lab with vastly different behavior. The one on Windows 10 Pro for Workstations (which is based on a newer Windows build) has been rock sold - so much that he was quite tempted to suggest customers use Windows 10 instead of Windows 2016! But an identical setup with Windows 2016 was still locking up every now and then up until KB4343884 was installed. So, I'm very optimistic about it, even if of course only the field experience will be able to confirm the resolution for sure. But until then, I recommend "business as usual" particularly in regards to physical RAM on your backup repository servers.