issue_comments: 343335659

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https://github.com/pydata/xarray/issues/1225#issuecomment-343335659 https://api.github.com/repos/pydata/xarray/issues/1225 343335659 MDEyOklzc3VlQ29tbWVudDM0MzMzNTY1OQ== 1217238 2017-11-10T00:23:32Z 2017-11-10T00:23:32Z MEMBER

Doing some digging, it turns out this turned up quite a while ago back in #156 where we added some code to fix this.

Looking at @tbohn's dataset, the problem variable is actually the coordinate variable 'time' corresponding to the unlimited dimension: ``` In [7]: ds.variables['time'] Out[7]: <class 'netCDF4._netCDF4.Variable'> int32 time(time) units: days since 2000-01-01 00:00:00.0 unlimited dimensions: time current shape = (5,) filling on, default _FillValue of -2147483647 used

In [8]: ds.variables['time'].chunking() Out[8]: [1048576]

In [9]: 2 ** 20 Out[9]: 1048576

In [10]: ds.dimensions Out[10]: OrderedDict([('veg_class', <class 'netCDF4._netCDF4.Dimension'>: name = 'veg_class', size = 19), ('lat', <class 'netCDF4._netCDF4.Dimension'>: name = 'lat', size = 160), ('lon', <class 'netCDF4._netCDF4.Dimension'>: name = 'lon', size = 160), ('time', <class 'netCDF4._netCDF4.Dimension'> (unlimited): name = 'time', size = 5)]) ```

For some reason netCDF4 gives it a chunking of 2 ** 20, even though it only has length 5. This leads to an error when we write a file back with the original chunking.

 
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