Do not allow im datasets to be created from blockstores that use all avail space
Had this problem today, a user create a zero size local blockstore, which means all available space. The user then created an image backed dataset from it, and it worked cause the amount of actual data was under out 10G (compressed) limit, but that image could not be loaded cause of an off by one error. That is easy to fix, but @mike says "f someone did that on a dss7500 node it would create a 270TB filesystem" which seems like a bad idea for an image backed dataset.