private long dirSize() throws IOException {
long ret = 0;
ShardedJedis rds = redisPool.getResource();
Map<byte[], byte[]> lst = rds.hgetAll(getDirNameBytes());
if( lst == null || lst.size() < 1)
return 0;
for(byte[] sz: lst.values() ){
try{ ret += ByteBuffer.wrap(sz).asLongBuffer().get(); }catch(Exception e){}
}