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 was able to patch the builder code in my notebook before the load data call and it works. 
```
import datasets
datasets.builder.has_sufficient_disk_space = lambda needed_bytes, directory='.': True
``` import datasets
    datasets.builder.has_sufficient_disk_space = lambda needed_bytes, directory='.': True
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?