The help tip description for this setting states 'The minimum free space available to allow writing to any disk belonging to the share.'

Does this include any cache drive that might be part (or the whole) of a share, or just array drives?

 

 

In the general case, Unraid doesn't know how large a file will become when it chooses a disk for it when writing to User Shares. If a disk has less than Minimum, another disk will be chosen if other factors allow it.

 

Cache and other pools have their own Minimum Free setting. If the pool has less than Minimum, an array disk (overflow) will be chosen instead for cache-prefer and cache-yes shares.

 

You must set Minimum Free to larger than the largest file you expect to write to the share or pool.

 

Note that Minimum Free doesn't control how much space Unraid keeps free on a disk, it only controls whether or not a disk can be chosen when writing User Shares.