Hi Hojjat,
I thought that it will be worse but you still have poor disk performance on your server.
I can see this:
Highest Latency: 25ms
Read rate: max. 25MB/s
Write rate: max. 50MB/s
Usage: 75MB/s (read + write)
Why is write rate twice larger than read rate?
Because hypervisor zeroes disc space before writing data. This is design, safety reasons.
Of course if controller have cache and battery zero fill is ignored and it will never be written to disk surface.
In addition, ESXi waits for write operation confirmation.
If you have controller with cache and battery and if write back cache mode is enabled (default),
hypervisor gets this confirmation without delay.
Result:
Your disc subsystem have maximum rate 25MB/s only a this is very slow speed !
I can see values up to 90MB/s on my notebook with antivirus.
Solution:
Buy raid controller with cache and battery.