PC1/PC2 does not error with too little disk space

[vmx]

I propose introducing an early error when there is not enough disk space available to perform PC1.

I tried to run PC1/PC2 via bin/seal configured with a single 7TiB NVMe to run 64 32GiB sectors. The disk space should by far be not enough. I would've expected an error message early on that there's not enough space available. Instead there doesn't seem to be any progress being made. I ran it for 16h or so and it didn't produce any output files.

[Howard-Hu]

The minimum disk space required to run PC1/PC2 (64 sectors of 32GiB each) is:

1. NVMe drive: 32GiB * 11 * 64 = 22TiB
2. Filesystem drive: 69GiB (sealed file, tree-C, tree-R total) * 64 = 4.5TiB