All was ran on the very same hardware (repository configured as CiFS to use fast cloning feature), we have 4 servers like this:
- HP DL380 Gen9 with dual CPU Intel E5-2660 v4 2Ghz, 64 GB of RAM, raid 1 SSD for the OS
- Dual 10 Gbit network cards (HP 560FLR) supporting the offloading of SMB v3 (RDMA capabale)
- 2 x DAS HP D3700 with 25 x 1.8TB 12G 10K SAS disks configured as Raid 6 with HP p441 controller
To hit those numbers I used the diskspd utility to do some benchmarking before validating the final repository setup.
If you have never used it, Veeam has done a great job explaining the different parameters you can use to simulate the different type of Veeam backup jobs: https://www.veeam.com/kb2014
With write only on my setup could go as high as 1.8GB/s. But with transforms, which is a 50% reads / 50% writes, that could go as low as 250MB/s.
My issues with ReFS started when I had several jobs (6 to 10) running at the same time on the same repository. Backups would not finish during the night.
I have reformated everything to NTFS, I can now run 20 jobs in parallel without any performance issue, and backup file merge is faster with NTFS than with fastcloning when several jobs run at the same time.
So according to my experience, ReFS works good if you have no job concurrency, if it is the case, performances start to drop dramatically.
Have you tested with NTFS to see if it's better ?