Bringing You Up to Speed: The History Lesson

Everyone remembers their first bike right? Mine was red. It had training wheels. I never really learned how to ride it, not that I didn’t go outdoors, I was just too afraid to take those training wheels off I guess. That was a long time ago, but I remember my first bike.

I also remember my first SSD. It was a 1.8” PATA drive made by Samsung for the MacBook Air. It was lent to me by a vendor so I could compare its performance to the stock 1.8” mechanical HDD in the Air.

The benchmarks for that drive didn’t really impress. Most application tests got a little slower and transfer speeds weren’t really any better. Application launch times and battery life both improved, the former by a significant amount. But the drive was expensive; $1000 from Apple and that’s if you bought it with the MacBook Air. Buying it from a vendor would set you back even more. It benchmarked faster than hard drive, but the numbers didn’t justify the cost. I pulled the drive out and sent it back after I was done with the review.

The next time I turned on my MacBook Air I thought it was broken. It took an eternity to boot and everything took forever to launch. Even though the benchmarks showed the SSD shaving off a few seconds of application launch time here and there, in the real world, it was noticeable. The rule of thumb is that it takes about a 10% difference in performance for a user to notice. The application tests didn’t show a 10% difference in performance, but the application launch tests, those were showing 50% gains. It still wasn’t worth $1000, but it was worth a lot more than I originally thought.

It was the MacBook Air experience that made me understand one important point about SSDs: you don’t think they’re fast, until I take one away from you.

My second SSD was a 60GB SuperTalent drive. I built a HTPC using it. It was my boot drive and I chose it because it drew less power and was silent; it helped keep my HTPC cool and I wouldn’t have to worry about drive crunching while watching a movie. My movies were stored elsewhere so the space didn’t really matter. The experience was good, not great because I wasn’t really hitting the drive for data, but it was problem-free.

SuperTalent was the first manufacturer to sell a SSD in a 3.5” enclosure, so when they announced their 120GB drive I told them I’d like to do a review of their SSD in a desktop. They shipped it to me and I wrongly assumed that it was the same as the 60GB drive in my HTPC just with twice the flash.

This drive did have twice the flash, but it was MLC (Multi-Level Cell) flash. While the 60GB drive I had was a SLC drive that used Samsung’s controller, the MLC drive used a little known controller from a company called JMicron. Samsung had a MLC controller at the time but it was too expensive than what SuperTalent was shooting for. This drive was supposed to be affordable, and JMicron delivered an affordable controller.

After running a few tests, the drive went in my Mac Pro as my boot/application drive. I remembered the lesson I learned from my first SSD. I wasn’t going to be able to fairly evaluate this drive until I really used it, then took it away. Little did I know what I was getting myself into.

The first thing I noticed about the drive was how fast everything launched. This experience was actually the source of my SSD proof-of-value test; take a freshly booted machine and without waiting for drive accesses to stop, launch every single application you want to have up and running at the same time. Do this on any system with a HDD and you’ll be impatiently waiting. I did it on the SuperTalent SSD and, wow, everything just popped up. It was like my system wasn’t even doing anything. Not even breaking a sweat.

I got so excited that I remember hopping on AIM to tell someone about how fast the SSD was. I had other apps running in the background and when I went to send that first IM and my machine paused. It was just for a fraction of a second, before the message I'd typed appeared in my conversation window. My system just paused.

Maybe it was a fluke.

I kept using the drive, and it kept happening. The pause wasn’t just in my IM client, it would happen in other applications or even when switching between apps. Maybe there was a strange OS X incompatibility with this SSD? That’d be unfortunate, but also rather unbelievable. So I did some digging.

Others had complained about this problem. SuperTalent wasn’t the only one to ship an affordable drive based on this controller; other manufacturers did as well. G.Skill, OCZ, Patriot and SiliconPower all had drives shipping with the same controller, and every other drive I tested exhibited the same problem.

I was in the midst of figuring out what was happening with these drives when Intel contacted me about reviewing the X25-M, its first SSD. Up to this point Intel had casually mentioned that their SSD was going to be different than the competition and prior to my JMicron experience I didn’t really believe them. After all, how hard could it be? Drive controller logic is nowhere near as complicated as building a Nehalem, surely someone other than Intel could do a good-enough job.

After my SuperTalent/JMicron experience, I realized that there was room for improvement.

Drive vendors were mum on the issue of pausing or stuttering with their drives. Lots of finger pointing resulted. It was surely Microsoft’s fault, or maybe Intel’s. But none of the Samsung based drives had these problems.

Then the issue was cache. The JMicron controller used in these drives didn’t support any external DRAM. Intel and Samsung’s controllers did. It was cache that caused the problems, they said. But Intel’s drive doesn’t use the external DRAM for user data.

Fingers were pointed everywhere, but no one took responsibility for the fault. To their credit, OCZ really stepped up and took care of their customers that were unhappy with their drives. Despite how completely irate they were at my article, they seemed to do the right thing after it was published. I can’t say the same for some of the other vendors.

The issue ended up being random write performance. These “affordable” MLC drives based on the JMicron controller were all tuned for maximum throughput. The sequential write speed of these drives could easily match and surpass that of the fastest hard drives.

If a company that had never made a hard drive before could come out with a product that on its first revision could outperform WD’s VelociRaptor and be more reliable thanks to zero moving parts...well, you get the picture. Optimize for sequential reads and writes!

The problem is that modern day OSes tend to read and write data very randomly, albeit in specific areas of the disk. And the data being accessed is rarely large, it’s usually very small on the order of a few KB in size. It’s these sorts of accesses that no one seemed to think about; after all these vendors and controller manufacturers were used to making USB sticks and CF cards, not hard drives.

  Sequential Read Performance
JMicron JMF602B MLC 134.7 MB/s
Western Digital VelociRaptor 300GB 118 MB/s

 

The chart above shows how much faster these affordable MLC SSDs were than the fastest 3.5” hard drive in sequential reads, but now look at random write performance:

  Random Write Latency Random Write Bandwidth
JMicron JMF602B MLC 532.2 ms 0.02 MB/s
Western Digital VelociRaptor 300GB 7.2 ms 1.63 MB/s

 

While WD’s VelociRaptor averaged less than 8ms to write 4KB, these JMicron drives took around 70x that! Let me ask you this, what do you notice more - things moving very fast or things moving very slow?

The traditional hard drive benchmarks showed that these SSDs were incredible. The real world usage and real world tests disagreed. Storage Review was one of the first sites to popularize real world testing of hard drives nearly a decade ago. It seems that we’d all forgotten the lessons they taught us.

Random write performance is quite possibly the most important performance metric for SSDs these days. It’s what separates the drives that are worth buying from those that aren’t. All SSDs at this point are luxury items, their cost per GB is much higher than that of conventional hard drives. And when you’re buying a luxury anything, you don’t want to buy a lame one.

  Cost Per GB from Newegg.com
Intel X25-E 32GB $12.88
Intel X25-M 80GB $4.29
OCZ Solid 60GB $2.33
OCZ Apex 60GB $2.98
OCZ Vertex 120GB $3.49
Samsung SLC 32GB $8.71
Western Digital Caviar SE16 640GB $0.12
Western Digital VelociRaptor 300GB $0.77
Index Why You Should Want an SSD
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  • Iger - Wednesday, March 25, 2009 - link

    This is the best review I've read in a very long time.
    Thank you very much!
    Reply
  • BailoutBenny - Tuesday, March 24, 2009 - link

    Great in depth article on flash based SSDs. I'm waiting for PRAM though. Reply
  • orclordrh - Tuesday, March 24, 2009 - link

    Very illuminating article, very well written and researched. It made me glad that I didn't pull the trigger on an SSD for my I7 machine and regret not buying OCZ memory! I'm interested in adding an SSD as the scratch disk for Photoshop CS4 to use. I don't really launch applications very often, say once a week on the weekly reboot and keep 6-8 apps open at all times. I have 12GB of memory for that. The benchmarks were very interesting, but what sort of activity does Photoshop scratch usage create? Large files or random writes? What type of SSD would be most cost effective here?
    An SSD does sound better than a SSD!
    Reply
  • semo - Wednesday, March 25, 2009 - link

    wait for ddr3 to enter the mainstream and buy loads of memory.

    use a ramdisk for your adobe scratch area. much faster than ssd and no wear to worry about (not that you would worry that much with modern ssds anyway).

    http://www.ghacks.net/2007/12/14/use-a-ramdisk-to-...">http://www.ghacks.net/2007/12/14/use-a-ramdisk-to-...

    there is also a paid for and more feature rich ramdisk out there. can't remember the name
    Reply
  • strikeback03 - Wednesday, March 25, 2009 - link

    I'll have to check when I get home, but I believe the recommended size for the scratch disk is upwards of 10GB. So would need a motherboard that supports a LOT of RAM to give enough to main memory plus a scratch disk. Reply
  • strikeback03 - Wednesday, March 25, 2009 - link

    I was wondering the same thing. I'd guess it would be a lot of writing/erasing, so an SSD might not be the best from a longevity standpoint, but if your system is hitting the scratch disk often then the speed might make it worthwhile. Reply
  • mikepers - Tuesday, March 24, 2009 - link

    Anand,

    I wanted to compliment you on what I think was an excellent article. This is the type of thing I really have always liked from Anandtech. The detailed background, the technical reasons for the issues and then a thorough review of the current state of things.

    I just finished upgrading my desktop. The only remaining item I wanted to replace was the hard disk. I had been thinking about getting a Velociraptor but instead I just ordered a 60GB Vertex from Newegg.

    Thanks again for all the work.

    Mike P.
    Reply
  • ameatypie - Monday, March 23, 2009 - link

    That sure was a lot to take in! Fantastic article though, it has really opened my eyes to the possibilities that Solid State Drives provide. Probably wont be buying one in the immediate future given the so-called depression and such things, but i will certainly keep up with SSD progress.
    Thanks again for your fantastic articles - im sure im not the only one who really appreciates them :)
    Reply
  • coopchennick - Monday, March 23, 2009 - link

    Hey Anand, I just finished reading through this whole article and I'm very impressed with the thoroughness and how informative it was.

    You just acquired a new regular reader.
    Reply
  • zdzichu - Sunday, March 22, 2009 - link

    Very nice and thorough article. I only lack more current status of TRIM command support in current operating systems. For example, Linux supports it since last year:

    http://kernelnewbies.org/Linux_2_6_28#head-a1a9591...">http://kernelnewbies.org/Linux_2_6_28#h...a9591f48...
    Reply

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