Is it possible to use fsspec filecache with the to_zarr method?

[josephnowak]

I was testing the filecache option of fsspec (for caching some files locally) and it worked really nice but when I try to write it, it throws a KeyError: '.zmetadata', so I was wondering if it is possible to use that option, I think it should first write the files locally and then move them to the original location or write them directly on that location.

small code:

import dask 
import fsspec 

import dask 
import fsspec 

s3_map = fsspec.get_mapper(
    's3://only-test-1',
    client_kwargs={
        'aws_access_key_id': aws_access_key_id,
        'aws_secret_access_key': aws_secret_access_key,
        'region_name': region_name
    }
)

cache_s3_map = fsspec.filesystem(
    "filecache", 
    fs=s3_map.fs,
    cache_storage='test_cache',
).get_mapper('s3://only-test-1')

dataset = xr.Dataset({
    'first': xr.DataArray(
        dask.array.arange(3*4).reshape((3, 4)),
        dims=['a', 'b'],
        coords={'a': list(range(3)), 'b': list(range(4))}
    )
})

# this produce the KeyError
cache_s3_map = cache_s3_map.fs.get_mapper(cache_s3_map.root + '/first')
dataset.to_zarr(cache_s3_map, mode='w')

# this is a regular write so it works
sub_map = s3_map.fs.get_mapper(s3_map.root + '/first')
dataset.to_zarr(s3_map, mode='w')

# This is strange for me, it works but it is slower, I don't know why.
dataset.to_zarr(cache_s3_map, group='first', mode='w')

[josephnowak]

After reading with more details the documentation of fsspec I found that the only protocol with local cache that can be used also for writing is the "simplecache" but even using that protocol I get some errors like ValueError: parameter 'value': expected array with shape (14,), got (6131,) and if I use the map without cache works perfectly.