how to see your hard disk i/o performance? iotop

iotop -oPa

 Total DISK READ :       0.00 B/s | Total DISK WRITE :     105.77 K/s
Actual DISK READ:       0.00 B/s | Actual DISK WRITE:      52.89 K/s
  PID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>    COMMAND                                                                                                                                     
 2269 be/4 postgres      0.00 B    120.00 K  0.00 %  0.48 % postgres: wal writer process
  991 be/3 root          0.00 B     44.00 K  0.00 %  0.06 % [jbd2/dm-1-8]
  877 be/4 root          0.00 B      0.00 B  0.00 %  0.01 % [kworker/0:2]
 3072 be/4 postgres      0.00 B     56.00 K  0.00 %  0.00 % postgres: odoo sgecfe [local] idle in transaction
 2070 be/4 root          0.00 B      4.00 K  0.00 %  0.00 % rsyslogd -n 

You can execute dd to write one file and see iotop

dd if=/dev/zero of=diskbench bs=1M count=1024 conv=fdatasync

Funte: 

https://haydenjames.io/linux-server-performance-disk-io-slowing-application/