If you want to see your server’s harddisk’s write and read speed,

Install hdparm first;

yum install hdparm

Then you can check the speed of your HDD’s by pointing their locations like;

hdparm -Tt /dev/vda1

The output will be like that:

/dev/vda1:
Timing cached reads: 18038 MB in 1.99 seconds = 9052.72 MB/sec
Timing buffered disk reads: 5498 MB in 3.00 seconds = 1832.66 MB/sec

That means my /dev/vda1 HDD has the ability to read around 9GB/sec and to write 1.8GB/sec.