I am facing strange behaviour of iostat command and top command. where initially it is showing high utilization and after it is showing low utilization.

iostat command

avg-cpu: %user %nice %system %iowait %steal %idle
73.60 0.01 23.93 0.92 0.00 1.54

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.35 0.09 0.50 2.04 10.50 21.30 0.00 1.29 0.19 0.01
sdb 0.04 3.07 0.27 4.12 8.20 73.39 18.62 0.00 0.69 0.18 0.08
sdc 0.26 0.46 0.31 7.42 155.19 850.85 130.10 0.07 9.00 0.40 0.31
sdd 0.00 0.00 2.40 1.00 5.73 1.01 1.98 0.00 0.38 0.37 0.13
sdf 0.00 0.00 2.40 1.00 5.74 1.01 1.98 0.00 0.38 0.37 0.13
sde 0.00 0.00 2.40 1.00 5.74 1.01 1.98 0.00 0.38 0.37 0.13
sdg 0.00 0.01 10.20 4.58 529.39 159.60 46.63 0.01 0.84 0.45 0.67
sdh 0.08 0.16 63.83 63.13 4792.88 1946.14 53.08 0.15 1.17 0.23 2.92
sdi 0.00 0.01 0.93 0.26 236.48 260.57 420.04 0.03 25.61 0.67 0.08

avg-cpu: %user %nice %system %iowait %steal %idle
0.89 0.00 0.76 0.00 0.00 98.35

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdc 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdd 0.00 0.00 2.00 1.00 2.00 1.00 1.00 0.00 0.33 0.33 0.10
sdf 0.00 0.00 2.00 1.00 2.00 1.00 1.00 0.00 0.33 0.33 0.10
sde 0.00 0.00 2.00 1.00 2.00 1.00 1.00 0.00 0.33 0.33 0.10
sdg 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdh 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdi 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

avg-cpu: %user %nice %system %iowait %steal %idle
2.15 0.00 0.63 0.00 0.00 97.22

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdc 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdd 0.00 0.00 2.00 1.00 2.00 1.00 1.00 0.00 0.67 0.67 0.20
sdf 0.00 0.00 2.00 1.00 2.00 1.00 1.00 0.00 0.33 0.33 0.10
sde 0.00 0.00 2.00 1.00 2.00 1.00 1.00 0.00 0.33 0.33 0.10
sdg 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdh 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sdi 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00



top
top - 11:15:06 up 16 days, 19:04, 3 users, load average: 0.18, 0.24, 0.23
Tasks: 260 total, 1 running, 259 sleeping, 0 stopped, 0 zombie
Cpu(s): 51.1%us, 34.6%sy, 0.3%ni, 11.5%id, 2.1%wa, 0.0%hi, 0.5

but after a while it is showing low.

top - 11:15:59 up 16 days, 19:05, 3 users, load average: 0.26, 0.25, 0.23
Tasks: 259 total, 1 running, 258 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.5%us, 0.3%sy, 0.0%ni, 99.2%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st

I have checked /var/log/messages, can not found any issues.

using oracle Linux 6.7

So, let's see if we can break this down:

• Your server runs some piece of code/something
• It gets busy (that is, it is now under load)
• The code finishes
• It is NOT busy anymore (that is, NOT under load)

...and you're confused about this why? Also, again, you've been here about NINE YEARS now, and have asked MANY questions almost identical to this. At what point are YOU, PERSONALLY going to be able to learn on your own, and apply the things you've been told over the years, in all these threads?
http://www.linuxquestions.org/questi...ut-4175581081/
http://www.linuxquestions.org/questi...6/#post5427436
http://www.linuxquestions.org/questi...on-4175458903/
http://www.linuxquestions.org/questi...on-4175552663/
http://www.linuxquestions.org/questi...memory-625772/
http://www.linuxquestions.org/questi...zation-640241/
http://www.linuxquestions.org/questi...-usage-920167/
http://www.linuxquestions.org/questi...zation-933553/
So there are no issues, yet you're trying to chase down a problem that isn't there? And you're using an OS that is commercial...have you called Oracle support, or do you not pay for the OS, as you should?

Again, you've been here for MANY years now.

The 1st sample of iostat is not current.

Top 10 process

ps -eo pcpu,pid,user,args | sort -k 1 -r | head -10

Same applies to top.