If you wish to know if HDD connected to your server is SSD (Solid State Drive) OR a normal HDD, you can simply login to your server via SSH & execute below command.
[root@server ~]# cat /sys/block/sda/queue/rotational
You should get 1 for normal HDD & 0 for a SSD (Solid State Drive). Linux automatically detected the SSD (Solid State Drive) with kernel 2.6.29 and later.