some context :
i'm using Veeam for many year and only on a SMB point of view.
For that, reverse incremental was wonderfull : the VBK file is containing the last data, so easy to export, put on tape and so on.
As many i went on ReFS to speedup merging (really impressive) but everything else is slow, and tape speed the biggest issue (in fact disk reads are to slow for tape) !
Then i read many post these last weeks and found so much informations. My problem is reported by many other ones that have same config (7200 SATA disks, RefS)
It seems to come at conclusion that reverse incremental is not good anymore (and could be stopped in future versions) i saw the user Gostev repeating this on different threads
I'm not able to do full backup (except for the first, obviously

Then i have some questions :
-1- Will Incremental and ReFS be faster at reading and then speedup my tape ?
-2- What should i do if i need 21 retention points ? 1 VBK and 20 VIB ? Synthetic full each week ? Will it take more space than my RI ? I'm a little bit afraid by forward incremental as i need to have all increments to restore yesterday file, RI is better for that
Thanks for clarifying, i'll keep on reading post as i learn so much !