How much extra space is required to restore the database

I added this question to google group mongodb , in the absence of an answer to it.

We have one instance of node mongo (version 2.0.1). We are running out of disk space even after daily archiving, since mongo does not return the space back to the OS and tries to use it on its own. At present, our installation has become very rare, about 50% of the free space. You can see that the data size + index is about 1170 GB, and the storage size is about 2158 GB, and the file size is about 2368 GB.

db.stats()    
{  
    "db" : "default",            
    "collections" : 106,  
    "objects" : 553988389,  
    "avgObjSize" : 2094.1392962010254,  
    "dataSize" : NumberLong("1160128855044"),  
    "storageSize" : NumberLong("2315777236208"),  
    "numExtents" : 1487,  
    "indexes" : 107,  
    "indexSize" : 97914435136,  
    "fileSize" : NumberLong("2543459500032"),  
    "nsSizeMB" : 16,  
    "ok" : 1  
}

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