Passed 1/5 RHCA: EX442 System Monitoring and Performance Tuning

I passed the first exam,EX442 System Monitoring and Performance Tuning,in my road to RHCA (Red Hat Certified Architect) today.
Here are some tips I can share, I think, without violating confidential agreement.
Document Source.
EX442 is very heavy on theory, you simply can't remember every bit ( and  its different unit: kb,byte,sector, block, bit,million secs, secs). The key is to  get them in the system documents without Googling.

#Man pages e.g
man 5 proc
#man pages keyword search
$ man -k semget
semget               (2)  - get a semaphore set identifier
semget               (3p)  - get set of XSI semaphores
#man pages full text search
$man -w -K SEMMNI
/usr/share/man/man5/proc.5.gz
/usr/share/man/man2/semget.2.gz
#/usr/share/doc, full text search
$yum install kernel-doc
$grep -ri isolcpus /usr/share/doc/kernel-doc*/Documentation/.* 
/usr/share/doc/kernel-doc-2.6.18/Documentation/kernel-parameters.txt:   isolcpus=       [KNL,SMP] Isolate CPUs from the general scheduler.
#Other documentations in html/pdf/info/ps format
$rpm -ql valgrind | grep /usr/share
..
/usr/share/doc/valgrind-3.5.0/html/index.html
..
$elinks /usr/share/doc/valgrind-3.5.0/html/index.html

Make the change persistent

#always put the change in configuration file first, then run the command to activate the change 
- Startup service: chkconfig svc-name on; service svc-name start
- User auto start script: edit /etc/rc.local;  execute “/etc/rc.local”
- Kernel Parameter: edit /etc/sysctl.conf; execute “sysctl -p”
- File system: edit /etc/fstab ; mount -a
- Kernel modules: edit /etc/sysconfig/modules/XXX.modules;   execute  “/etc/sysconfig/modules/XXX.modules”

Calculator:

#You got to know how to use bc.
#Always start with bc with “-l” option to support floating  point.
#e.g 1Gibit=131072KiByte
$ bc -l
1*2^30/1024/8
131072.00000000000000000000
#if there are too many to be added up, you got to use awk
#e.g  sum and average value calculated from 1 to 1000
$ echo {1..1000} | sed "s/ /\n/g" | awk ' {x=$1+x} END {print $1,x,x/NR } '
1000 500500 500.5
#convert  hexadecimal  value  to decimal  
#the hex letter must be in upper case
$echo -e " obase=10 \n ibase=16 \n 0F0" | bc -l
240

Time is essence, every minute counts, you got to master bash command line.
Check this: http://honglus.blogspot.com/2010/07/master-bash-command-line.html
lastly, the Exam day
 - take your RHCE number with you
 - there are a couple of tricky questions, I finished all, I thought I could get 90, but I only got 80. I don't know what went wrong.
 - Unlike RHCE exam, which has 2 sessions with a break for lunch, the EX442  only has 1 morning  session  last for 4 hours
 - Exam result will be emailed in 2 business days, but I got mine in 2 hours.


My Blog posts for EX442 study notes
Load kernel modules at boot time on Redhat/Centos Linux.
Tune Interrupt and Process CPU affinity
Understanding Linux CPU scheduling priority

Calculate chunk size for RAID device

Setup SNMP V3 USM with encryption.

Graphing sar output

Linux memory management study notes