Well the ddrescue had been atempted. And i live hard die fast or something , no image just plain disk to disk clone .
Size of the drives is identical to a single byte.
Initially ddrescue designated around 8mb as problematic of which it recovered 6 and slightly less than 2mb was in bad sectors. Therefore i think gone. How much of it was on free space and how much in data holding area i can't tell. But most wear was between 70 and 85% of the drive where read error count jumped from 30 to 130 and first pass finished with only one read error more. (after advanced data recovery pases ddrescue reported around 5000 read errors trough wgole process)
That being said we don't care about how many error it had but did it worked, and yes it did.
Initially array self assembled with the copy but volume remained missing, but this time runing ckdsk on it let it do the job and filesystem is back, mounted and files seems to be on it.
How many of them are corrupted i will only know when i find one, but there is some redundency and i don't really need everything.
There is one conspicuous empty folder, but it might been empty for a while , there is no random extra files, no silly names.
Either checkdisk unceremonially removed all corupted files, or i was lucky
Since schools in my region have very tight budget on non esential equipment, i will probably have no budget for new drives untill december, but i will make regular backups from now on.
The only other option to replace the drives i have now is to swap them with barely used laptop toshibas mq01abd100 of which i have 15 laying around, but that bad idea of itself even in raid 1+0 configuration (server only have 5 sata ports and one is for system boot drive (which is even older) so the size would be still only 1,8TB ) i don't think running laptop drives 24/7 would work long term and they might not even live untill december, but maybe i am biased. Nothind stoping me from using them as backup usb drives though.
For now i think the raid is saved and there is no much more to be done to improve it. I will pull the data of next trough network since there is no other way. And if you think raid 1+0 of 2,5 inch 1tb slightly used laptop drives is better than running raid 0 of ancient desktop drives i might do that.
As for smart sheduled checks i had no idea that is a thing untill recently so of course there was never any of them scheduled or performed. Server wasn't even planed to exist. It was hastly assembled 3 years ago from junked vista computer, got 2 extra gigabit nics, i think at one point it even had 5, but the network is bottlenecked at 1gbps by goverment program "new network equipment", and we ended up with just feeding 3 separate networks at 1gbps instead of bundling the bandwidth into one so harddrives didn't even utilize full raid0 speed over network. And server just kind of remainded operating since one of the teachers asked me to keep it. Probably gobbles power like a champ for a job rawsberry pi would do faster too.
Thanks Krisbee you really saved my bacon this time. if you think my dodgy raid 1+0 of laptop drives is a better option let me know, because otherwise they will just rot in the box