You may have observed https://issues.apache.org/jira/browse/HDFS-1601.
On Fri, Jan 28, 2011 at 7:08 PM, Da Zheng <[EMAIL PROTECTED]> wrote:
> I monitored system calls of HDFS with systemtap and found HDFS actually
> many 1-byte data to the network. I could also see many 8-byte and 64-byte
> written to the OS though I don't know whether they are written to the disk
> sent to the network. I did see many 8-byte data sent to the network. The
> of these data is several times more than 64KB data packet sent by HDFS.
> Could anyone tell me why HDFS sends so many small packets? heartbeat
> RPCs? It doesn't seem to me these messages can be just 1 byte.