Generate i/o load on your vm and use iostat to demonstrate the increased in i/o

Transcription

1 Jae Sook Lee SP17 CSIT Dr. Chris Leberknight iostat Generate i/o load on your vm and use iostat to demonstrate the increased in i/o Terminal # 1 iostat -c -d -t > JaeSookLee_iostat<number>.txt -c <option>: Display only the CPU usage statistics -d <option>: Displays only the disk i/o statistics -t <option>: Timestamp information display current time, Terminal # 2 dd if=/dev/zero of=/root/testfile bs=512 count=1000 oflag=dsync dd stand for data duplicator: used to monitor the writing performance of disk device on linux <if=/dev/input.file> if stand for input-file: this is source from where you want to copy data <of=/path/to/output.file> of stands for output-file: this is source from where you want to write/paste data 1

2 <bs=block-size> set the size of block that dd to use. <count=number-of-blocks> the number of blocks you want dd to read <oflag=dsyn> use for synchronized i/o for data. It will get rid of caching and gives accurate results. iostate outputs The output of 3 different block-sizes, 350, 750, and 1050 are captured by command iostat -c -d -t > JaeSookLeeiostate<blocksize>.txt which included CPU usage, disk i/o statistic, and time options. It collected data every 2 second and 100 times. As I mentioned above, the size of block writing performance of local disk device. All of them has increased CPU activities whish is %idle CPU percentage of time and %iowait. In this iostat generate case, %kb_written is mostly changed which is total amount of data written from the device and %tps which is transfers per second. In summary, Each blocks, 350,750, and 1050, doesn t decrease time which means hard drive took the same time to write regardless size of blocks. %iowait displays CPU wait until hard drive writing. In this case, CPU wait time is increased and close to approximately 99% to 100%. CPU writing time is much faster than hard drive writing. Even if increase number of job, block size, CPU wait time is faster than hard drive. Terminal #1 iostat1050.txt Terminal #2 dd if=/dev/zero of=/root/testfile bs=1050 count=1000 oflag=dsync Linux generic (u20) 02/22/2017 _i686_ (1 CPU) 02/22/ :50:15 PM 02/22/ :50:17 PM vda dm /22/ :50:19 PM vda dm /22/ :50:21 PM

3 vda dm /22/ :50:23 PM vda dm /22/ :50:25 PM vda dm /22/ :50:27 PM vda dm /22/ :50:29 PM vda dm /22/ :50:31 PM vda dm /22/ :50:33 PM vda dm /22/ :50:35 PM vda dm

4 02/22/ :50:37 PM vda dm /22/ :50:39 PM vda dm /22/ :50:41 PM vda dm /22/ :50:43 PM vda dm /22/ :50:45 PM vda dm /22/ :50:47 PM vda dm /22/ :50:49 PM vda dm /22/ :50:51 PM

5 vda dm /22/ :50:53 PM 02/22/ :50:55 PM Terminal #1 iostat750.txt Terminal #2 dd if=/dev/zero of=/root/testfile bs=750 count=1000 oflag=dsync Linux generic (u20) 02/22/2017 _i686_ (1 CPU) 02/22/ :53:40 PM 02/22/ :53:42 PM vda dm /22/ :53:44 PM vda dm /22/ :53:46 PM vda dm

6 02/22/ :53:48 PM vda dm /22/ :53:50 PM vda dm /22/ :53:52 PM vda dm /22/ :53:54 PM vda dm /22/ :53:56 PM vda dm /22/ :53:58 PM vda dm /22/ :54:00 PM vda dm /22/ :54:02 PM 6

7 vda dm /22/ :54:04 PM vda dm /22/ :54:06 PM vda dm /22/ :54:08 PM vda dm /22/ :54:10 PM vda dm /22/ :54:12 PM vda dm /22/ :54:14 PM vda dm /22/ :54:16 PM vda dm

8 02/22/ :54:18 PM vda dm /22/ :54:20 PM 02/22/ :54:22 PM Terminal #1 iostat350.txt Terminal #2 dd if=/dev/zero of=/root/testfile bs=350 count=1000 oflag=dsync Linux generic (u20) 02/22/2017 _i686_ (1 CPU) 02/22/ :55:30 PM /22/ :55:32 PM vda dm /22/ :55:34 PM vda dm /22/ :55:36 PM

9 vda dm /22/ :55:38 PM vda dm /22/ :55:40 PM vda dm /22/ :55:42 PM vda dm /22/ :55:44 PM vda dm /22/ :55:46 PM vda dm /22/ :55:48 PM vda dm /22/ :55:50 PM vda dm

10 02/22/ :55:52 PM vda dm /22/ :55:54 PM vda dm /22/ :55:56 PM vda dm /22/ :55:58 PM vda dm /22/ :56:00 PM vda dm /22/ :56:02 PM vda dm /22/ :56:04 PM vda dm /22/ :56:06 PM 10

11 vda dm /22/ :56:08 PM vda dm /22/ :56:10 PM vda dm /22/ :56:12 PM vda