Affects Version/s: None
Fix Version/s: HDFS-7285
The default WritePacketSize is 64k
Currently default cellSize is 64k
We hope one cell consumes one packet. In fact it's not.
chunkSize = 516( 512 data + 4 checksum)
packetSize = 64k
chunksPerPacket = 126 ( See DFSOutputStream#computePacketChunkSize for details)
numBytes of data in one packet = 64512
cellSize = 65536
When first packet is full ( with 64512 data), there are still 65536 - 64512 = 1024 bytes left.
When the last 1024 bytes of the cell was written, we meet cellFull and create another packet.