Sounds simple, but is it simply a case of excluding disks? I now have my disks full to capacity with a margin, 5%, just in case. I've tried excluding every full disk but still shares are trying to use the 'margin' if free space with calamitous results. How do I just stop a disk from being picked for writes by the system? Told you it was simple 😏

So you don't want your disks to fill up beyond 95%?

47 minutes ago, Spies said:

So you don't want your disks to fill up beyond 95%?

Thats right ... but they do.

Why do you want it to work like that out of interest?

The content is now static. There's a couple of empty disks available but still content goes to the 'full' disks and then requires to be manually shifted, a real pita! I've tried the exclude/include trucks, doesn't seem to work. Min free space param, no luck there either. There must be a way to 'lockdown' a disk..

Edit the share and change Allocation Method to most free.

You also want to check the Split Level setting for the shares in question.    If there is contention between the various share settings for choosing a disk for a new file then the Split Level setting always wins.   Having a too restrictive value can make Unraid try to write a new file to a disk that does not have enough space for it.

Thanks. I'll give both suggestions a go.