Hey I was wondering since SSDs are so expensive, and your can buy a lot more hard drive with a lot more space for the same price as an SSD, how many average hard drive 7200RPM would it take in RAID, to equal an average SSD.
It all depends on your application. If you are concerned about boot times and game load times, then you will not be able to match the performance of an SSD. Applications that require random read or write performance will greatly benefit from an SSD. The seek times on these devices are 100-1000x faster than hard drives. For streaming performance, you can easily beat SSD's though. Good 7200 rpm drives are hitting 120MB/s so 2-3 of them should do. Of course this depends on the RAID level you use. RAID 5 would take another drive to match streaming read performance. I'm on the fence with SSD, holding out for the next gen. I just dont load apps or boot that often, so a few seconds here and there doesnt bother me.
I was considering going with a RAID set-up (I don't go gaming, but more apps like CS4, Office 07 - especially Access & Excel, etc). Anyways, I got some good feedback on the pros & cons of a RAID0 set-up and the consideration of an SSD. (I ended up getting the SSD and I'm really pleased). The apps I use most often are on the SSD and boot up in a split second. Those that are used less frequently and all my media are stored on my 1TB 7200.12 drive.
Here's the specific post that was helpful to me and the whole thread is there too... (I posted a lot of various specs from a Samsung F3 500GB in RAID0, a 1TB 7200.12 by itself, and then some SSD's and then the SSD I purchased). Artificial tests don't mean everything, but it may help give you some sort of baseline to start with...
SSD is what you want for speed. RAID will always fall well behind an SSD for random access speeds, but like goobaah said it can come close or beat it for sequential access. The advantage of RAID will be the capacity you can achieve.
Random Access *****
Sequential Access *****
Random Access **
Sequential Access ******
Goobah is right. The reason SSDs perform so much better is because they have a much faster access time - about 100X faster than a typical hard drive. Unfortunately, RAID does little or nothing to improve access times, no matter how many disks you have.
All that RAID does performance-wise is to improve transfer rates and concurrent I/O capability, neither of which have a very big effect on booting your system or starting up applications. RAID is great in a heavily-utilized server environment, but not of much use for a desktop computer (performance-wise) unless you often deal with very large files and can therefore benefit from the improved transfer rates.