Linux automatically detects SSD, and since kernel version 2.6.29, you may verify sda
with:
cat /sys/block/sda/queue/rotational
You should get 1
for hard disks and 0
for a SSD.
It will probably not work if your disk is a logical device emulated by hardware (like a RAID controller).
See this answer for more information about SSD partitioning, filesystem...