raid(5)-hdd poor performance vs single ssd drive

[brucehf]

i have a raid 5 configuration on HP gen9 server with 8 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 7 minutes.(maximum read speed=400 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=700 MB/s)

the question is: why performance difference is so big? (considering the amount of 10k disks in use)

[banhien]

@brucehf 

You are comparing SSD (no moving part) to HDD (with moving parts). Whichever way, SSD's are always faster than HDD's even they use SAME interface.

Regards.

[brucehf]

i know that, if i compare one SSD hard drive with one HDD (with moving parts), ssd is always better.

but if make a raid5 disk array with 10k HDD's , i expect more speedy performance.