Not enough disk space (Needed: Unknown size) when caching on a cluster
Hi ! 

What do you mean by "disk_usage(".").free` can't compute on the cluster's shared disk" exactly ?
Does it return 0 ? Yes, that's right. It shows 0 free space even though there is. I suspect it might have to do with permissions on the shared disk.

```python
>>> disk_usage(".")
usage(total=999999, used=999999, free=0)
``` That's an interesting behavior...
Do you know any other way to get the free space that works in your case ?
Also if it's a permission issue could you try fix the permissions and let mus know if that helped ? I think its an issue on the clusters end (unclear exactly why -- maybe something with docker containers?), will close the issue Were you able to figure it out? @philippnoah I had fixed it with a small hack where I patched `has_sufficient_disk_space` to always return `True`. you can do that with an import without having to modify the `datasets` package @olinguyen Thanks for the suggestion, it works but I had to to edit builder.py in the installed package. Can you please explain how were you able to do this using import?
I'm running some experiments where I'm caching datasets on a cluster and accessing it through multiple compute nodes. However, I get an error when loading the cached dataset from the shared disk.

The exact error thrown:

```bash
>>> load_dataset(dataset, cache_dir="/path/to/cluster/shared/path")
OSError: Not enough disk space. Needed: Unknown size (download: Unknown size, generated: Unknown size, post-processed: Unknown size)
```


[`utils.has_sufficient_disk_space`](https://github.com/huggingface/datasets/blob/8a03ab7d123a76ee744304f21ce868c75f411214/src/datasets/utils/py_utils.py#L332) fails on each job because of how the cluster system is designed (`disk_usage(".").free` can't compute on the cluster's shared disk).


This is exactly where the error gets thrown:
https://github.com/huggingface/datasets/blob/master/src/datasets/builder.py#L502

```python
if not utils.has_sufficient_disk_space(self.info.size_in_bytes or 0, directory=self._cache_dir_root):
    raise IOError(
          "Not enough disk space. Needed: {} (download: {}, generated: {}, post-processed: {})".format(
          utils.size_str(self.info.size_in_bytes or 0),
          utils.size_str(self.info.download_size or 0),
          utils.size_str(self.info.dataset_size or 0),
          utils.size_str(self.info.post_processing_size or 0),
       )
    )

```

What would be a good way to circumvent this? my current fix is to manually comment out that part, but that is not ideal. 
Would it be possible to pass a flag to skip this check on disk space?