The WARNing aims to act as a guideline to indicate that you may be facing hardware level trouble. Your values aren't excessively high to be extremely worried about, but to explain each of the two warnings: > Slow BlockReceiver write data to disk cost This is measured as the time taken to write to disk when a data packet comes in for a block write. Java-wise, its just the duration measurement behind an equivalent of "FileOutputStream.write(…)" call, which actually may not even target the disk in most setups, and go to the Linux buffer cache instead. It appears your writes to these disks seem too slow. I am not well versed with XFS, but we recommend use of EXT4. What is the meaning of "allocsize=128m" in your mount options BTW? Note that we do not write entire blocks at once into an open file, but write packets in a streaming manner (building towards the block size), and packet sizes range between 64k to 128k each. > Slow BlockReceiver write packet to mirror This measures the duration taken to write to the next DN over a regular TCP socket, and the time taken to flush the socket. We forward the same packet here (small sizes, like explained above). An increase in this typically indicates higher network latency, as Java-wise this is a pure SocketOutputStream.write() + SocketOutputStream.flush() cost. Hopefully these facts should help you tune your configuration better. Its likely to be a tuning issue than anything else, given the new hardware.
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