Originally Posted by ilovejedd
Hmm, do several virtual disk images containing various OSes count as data or OS? I think I'll refer to them as data. I plan on using a single 2.5" or mSATA SSD for the host OS. I find throughput on a single SSD even on SATA2 is more than sufficient for that.
Actually, I already have 4x Samsung 830 128GB and 2x Samsung 830 256GB SSDs on hand for testing. Those are the drives I'm planning to benchmark.
From this chart
, the Samsung 830 256GB gets 395MB/s in AS-SSD sequential while the Samsung 830 128GB gets 310MB/s when connected to a SATA3 port. Assuming perfect scaling, theoretical throughput of 2x256GB SATA3 in RAID-0 is around 790MB/s for sequential write. Most SATA3 SSDs I've seen (least the ones that can exceed SATA2 speed) have their sequential performance capped to 230~280MB/s when connected to SATA2. With perfect scaling, that translates to 920-1,120MB/s for a 4-way SATA II RAID-0. Of course, those are just theoretical speeds. That's why I'm planning on running benchmarks to see real world throughput.
For production use, I plan on only using 2x Samsung 830 256GB on SATA3 in RAID-0. Even if the 4-way RAID-0 is faster, I can't really give up the SATA ports. Of the 6 available Intel ports, I'll have 5 in use: 1x OS SSD, 2x RAID-0 data SSD and 2x RAID-1 backup HDD.
My experience has been that two larger SSD's in RAID0 are faster than 4 smaller SSD's in RAID0 on Sata II. I assumed the RAID controller just topped out...
It's not hard to hit 1000MB/sec with two larger sized quality SSD's in RAID 0 on SATA 3. I've done it with two OCZ 120GB's. I'm assuming you can hit that with 256GB Samsung 830's too..
64GB SSD's show the fastest percentage increase- but only because they are the slowest to start off. You essentially have a RAID controller inside every SSD, that splits the data to the different NAND chips inside. More NAND chips in larger SSD's means the reads/writes are split over more and thus the speed of the actual chips inside becomes less of an issue. My experience has taught me that 64GB SSD's and SSD's that have a cheaper or fewer NAND inside respond pretty well since your removing the bottle neck of how fast the NAND can perform when you add more drives and split the data across more simultaneous.
The 64GB/128GB/256GB have essentially the same controllers inside them- so the difference you see in the larger SSD's being faster is just simply the additional NAND providing a boost. The controller is less a limiting factor in smaller SSD's- and can generally outperform the NAND performance.
As you get into the larger and better SSD's your already seeing speeds much faster so the percentage increase is smaller- while the actual performance is still greater. I hope that makes sense.
I think you'll do about 700/MB sec on 4xSATAII and probably 950MB/sec on 2xsata3 with a good SSD.
I wiped clean my Max IOPS (hard clean, hard erase) so the NAND did not need to be deleted before being written- and I hit 1400MB/sec on my first benchmark in RAID0. That was two 120GB SSD's. My 120GB OCZ with toggle nand is probably about the same speed as the Samsung so I assume you can get about the same speeds. Possible a bit more since it's a 256GB- But I think the Marvel controller is a bit slower than the Sandforce when it behaves in RAID 0 so your mileage may vary.
Bottom line is usually in SSD performance the amount of NAND and the quality of NAND is the limiting performance factor that differentiates one SSD from another. In RAID0 and 120GB+ sized drives- the limited factor no longer becomes the NAND and it becomes the controllers. Both the RAID controller and the SSD controller depending on your set up will be your bottle neck.
Of coarse this bottleneck happens at speeds way faster than a normal consumer SSD single drive.
BTW- what exactly are you using this drive for? An OS installation? Virtual disk ?
And- it sounds to me like you would be better off with a PCI based SSD card. They are much faster, easier..... No SSD can touch that speed as PCI Cards have no bottleneck in connection. You speed would be limited to the size /controller and your performance ceiling is comfortably above any SSD on the market today.