7 nia San Diego, ‡Huazhong Univ. of Science & Technology, †NetApp, Inc tixu, longjin, xuf001, yyzhou}@cs.ucsd.edu kar.Pasupathy, Rukma.Talwadker}@netapp.com prevalent, but also severely software. One fundamental y of configuration, reflected parameters (“knobs”). With m software to ensure high re- aunting, error-prone task. nderstanding a fundamental users really need so many answer, we study the con- including thousands of cus- m (Storage-A), and hundreds ce system software projects. ng findings to motivate soft- ore cautious and disciplined these findings, we provide ich can significantly reduce A as an example, the guide- ters and simplify 19.7% of on existing users. Also, we tion methods in the context 7/2006 7/2008 7/2010 7/2012 7/2014 0 100 200 300 400 500 600 700 Storage-A Number of parameters Release time 1/1999 1/2003 1/2007 1/2011 0 100 200 300 400 500 5.6.2 5.5.0 5.0.16 5.1.3 4.1.0 4.0.12 3.23.0 1/2014 MySQL Number of parameters Release time 1/1998 1/2002 1/2006 1/2010 1/2014 0 100 200 300 400 500 600 1.3.14 2.2.14 2.3.4 2.0.35 1.3.24 Number of parameters Release time Apache 1/2006 1/2008 1/2010 1/2012 1/2014 0 40 80 120 160 200 2.0.0 1.0.0 0.19.0 0.1.0 Hadoop Number of parameters Release time MapReduce HDFS [Tianyin Xu, et al., “Too Many Knobs…”, FSE’15]