i have a raid 5 configuration on HP gen9 server with eight hard disks (hp-10k-1.2TB disks). that server intended to serve as a Microsoft SQL sever and contains a database with 143GB size.
i have run a time consuming query on it and it accomplished in 10 minutes.(maximum read speed=200 MB/s)
then i stored that database on a single SSD drive(Samsung EVO 1TB) and same query accomplished in 3 minutes.(maximum read speed=380 MB/s)
the question is: why performance difference is so big? (considering the amount of 10k disks in use)