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ep:labs:03:contents:tasks:ex2 [2020/08/03 16:27]
cristian.marin0805 created
ep:labs:03:contents:tasks:ex2 [2020/08/03 16:31] (current)
cristian.marin0805
Line 1: Line 1:
-salut+==== 02. [10p] Iostat ==== 
 + 
 +<note tip> 
 +Parameteres for iostat: 
 +    * -x for extended statistics 
 +    * -d to display device stastistics only 
 +    * -m for displaying r/w in MB/s 
 +<code bash> 
 +$ iostat -xdm 
 +</​code>​ 
 +Use iostat with -p for specific device statistics:​ 
 +<code bash> 
 +$ iostat -xdm -p sda 
 +</​code>​ 
 +</​note>​ 
 + 
 +=== [10p] Task A - Monitoring the behaviour === 
 +  * Run //iostat -x 1 5//. 
 +  * Considering the last two outputs provided by the previous command, calculate **the efficiency of IOPS** for each of them. Does the amount of data written per I/O **increase** or **decrease**?​ 
 + 
 +<​note>​ 
 +How to do: 
 + 
 +  * Divide the kilobytes read (//rkB/s//) and written (//wkB/s//) per second by the reads per second (//r/s//) and the writes per second (//​w/​s//​). 
 +  * If you happen to have quite a few [[https://​en.wikipedia.org/​wiki/​Loop_device|loop devices]] in your **iostat** output, find out what they are exactly: 
 + 
 +<code bash> 
 +$ df -kh /​dev/​loop* 
 +</​code>​ 
 +</​note>​ 
 + 
 + 
 +<​solution -hidden>​ 
 +The way to calculate the efficiency of IOPS is to divide the reads per second //(r/s)// and writes per second //(w/s)// by the kilobytes read //(rkB/s)// and written //(wkB/s)// per second. 
 + 
 +Example: the amount of data written per I/O for ///​dev/​sda//​ increases during each iteration:​ 
 + 
 +{{ :​ep:​labs:​ep2017_l3_ex01.png?​700 |}} 
 + 
 +<​code>​ 
 +53040/105 = 505KB per I/O 
 +71152/102 = 697KB per I/O 
 +</​code>​ 
 + 
 +If everything is zero in iostat - perform some I/O operations... 
 +</​solution>​
ep/labs/03/contents/tasks/ex2.txt · Last modified: 2020/08/03 16:31 by cristian.marin0805
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