Fig. 5 shows the results of total throughput measurements
with data logging. The x axis indicates the number of NEUNET
emulators and the y axis indicates throughput in MB/s. The closed
square data points show data logging with a single disk when
the dirty_background_ratio¼10, the default value of OS. The
dirty_background_ratio is the percentage of total memory at
which the background writeback daemon will start writing out
dirty data. The closed triangle data points show the condition of
a single disk when the dirty_background_ratio¼1. The closed
circle data points show the condition of stripping four disks
(chunk size¼512 kB) when the dirty_background_ratio equal¼1.
By adjusting the dirty_background_ratio¼1 and using stripping
disks to store data, we could meet the performance requirements
for a DAQ unit from MLF.