Explanation/Reference:
Explanation:
C: A useful command to get CPU related stats is mpstat. Here is an example output:
# mpstat -P ALL 5 2
Linux 2.6.9-67.ELsmp (oraclerac1) 12/20/2008
10:42:38 PM CPU %user %nice %system %iowait %irq %soft %idle intr/s
10:42:43 PM all 6.89 0.00 44.76 0.10 0.10 0.10 48.05 1121.60
10:42:43 PM 0 9.20 0.00 49.00 0.00 0.00 0.20 41.60 413.00
10:42:43 PM 1 4.60 0.00 40.60 0.00 0.20 0.20 54.60 708.40
etc.
D: When called, the grand-daddy of all memory and process related displays, vmstat, continuously runs and posts its information. It takes two arguments:
# vmstat <interval> <count>
<interval> is the interval in seconds between two runs. <count> is the number of repetitions vmstat makes.
Here is a sample when we want vmstat to run every five seconds and stop after the tenth run. Every line in the output comes after five seconds and shows the stats at that time.
# vmstat 5 10
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa
0 0 1087032 132500 15260 622488 89 19 9 3 0 0 4 10 82 5
0 0 1087032 132500 15284 622464 0 0 230 151 1095 858 1 0 98 1
0 0 1087032 132484 15300 622448 0 0 317 79 1088 905 1 0 98 0
... shows up to 10 times.
The output shows a lot about the system resources.
E: sar stands for System Activity Recorder, which records the metrics of the key components of the Linux system-CPU, Memory, Disks, Network, etc.-in a special place: the directory /var/log/sa.
The simplest way to use sar is to use it without any arguments or options. Here is an example:
# sar
Linux 2.6.9-55.0.9.ELlargesmp (prolin3) 12/27/2008
12:00:01 AM CPU %user %nice %system %iowait %idle
12:10:01 AM all 14.99 0.00 1.27 2.85 80.89
12:20:01 AM all 14.97 0.00 1.20 2.70 81.13
12:30:01 AM all 15.80 0.00 1.39 3.00 79.81
12:40:01 AM all 10.26 0.00 1.25 3.55 84.93
Incorrect:
Not A: iostat is for I/O