Now, back to Veeam and industry news – at least here I've something positive to share! Last week, Microsoft has released the patch resolving ReFS issues on Windows Server 2019 LTSC as KB4541331. Unlike the previous update from a few months ago, I have full confidence in this one, simply because a number of impacted Veeam customers were running the pilot version of this patch in their environments with great success – and Microsoft confirmed what was released publicly is the same code. Besides, at least one of those customers tested this patch against a few hundreds TB ReFS repository. Based on what I know, with this patch Server 2019 LTSC should provide better ReFS performance than even Server 2016 – because on top of fixing the primary root cause of the main issue with ReFS on Server 2019 now (regression due to Hyper-V I/O latency optimizations), Microsoft back-ported some ReFS optimizations from SAC version 1903 to Server 2019 LTSC back in the previous patch.
Now, if you're after bleeding edge ReFS performance, for example because you have extremely large or busy repositories, then version 1909 (which v10 fully supports) is still the way to go. This is because 1909 contains all the improvements which were back-ported to 2019 LTSC so far, plus quite a few additional enhancements to the core ReFS metadata engine, which makes it up to 3 times faster – as confirmed in the head to head real-world testing performed by mkretzer. Unfortunately, per Microsoft those additional optimizations are too much to back-port to 2019 LTSC, so I guess we will only see them in the next LTSC release. But it's not a big issue, as Server 2019 with KB4541331 should already be better than Server 2016, which in turn has been solid for our customers since September 2018 patches (we get little to no complaints even from the largest clients).
https://support.microsoft.com/en-us/help/4541331/windows-10-update-kb4541331