Introducing Solid State Hard Disks (SSDs)

I'm writing this posting on a laptop computer that is, literally, in my lap. As I type, the poor machine gets bounced around which is not at all good for the hard disk. I'm tempting fate, perhaps the computer equivalent of driving without a seat belt.

I would be much better off if the computer had a Solid State Hard Disk (SSD) rather than the traditional hard disk with rotating platters. Hard disks are amazing feats of technology, but they are moving mechanical devices and nothing good comes from bouncing them around, be it on your lap or carrying a notebook computer around the room while it's running.

No doubt more and more laptop computers will move away from rotating platter, traditional, hard disks to Solid State Hard Disks because, in may ways, SSDs are better.

Because SSDs use flash ram to store data, there is no risk of mechanical failure. And, even though hard disks spin pretty fast, compared to the other internal components they are serious slow pokes. As a rule of thumb, SSDs are faster than traditional hard disks, but more on this below.

More power is needed to make hard disk platters rotate than is needed to power the flash ram in SSDs. Thus, laptop users can get more run-time from the same sized battery. Or, a computer with an SSD can be smaller and lighter because the same run-time can be had with a physically smaller battery.

Rotating hard disks generate heat, which needs to be dissipated. Without this heat, laptop computer designers may be able to omit the fan making the computer smaller and quieter. This was the case with the original Asus EEE laptop computer.

The big thing holding back adoption of SSDs is, of course, the price. Today, for example, if you want an Apple MacBook Air, opting for the SSD adds $999 to the price.

Much of this is common knowledge. A couple blog postings by Matt Kohut of Lenovo have a lot to add.

First Generation SSDs

In his first blog about SSDs (see Solid State Hard Disk Drives) last August, Kohut noted that things were changing drastically between first generation and second generation Solid State Hard Disks. Tests by Lenovo concluded that first generation SSDs didn't cut the mustard which is why, at the time, they didn't offer SSDs on any of their laptop computers. Kohut says that Lenovo was waiting for assorted improvements offered by second generation SSDs.

I was surprised to read that in their testing Lenovo found no power savings with first generation SSDs, compared to traditional hard disks. How could this be? According to Kohut first generation SSDs:

"... with a Serial ATA interface are actually Parallel ATA hard disk drives with a serial bridge chip. They don't offer support for low power interface states and the architecture has a potential for data-losing error conditions when recovering from a low power state like suspend or hibernate."

One of the features Lenovo was waiting for in second generation SSDs were true SATA interfaces.

Read/write performance offered another interesting point. While first generation SSDs were very fast on random reads and slow on writes, it's not that simple. Quoting:

"Performance numbers are inconsistent and very dependent on factors like percentage of space used and file fragmentation. Those benchmarks with sequential reads or writes will have markedly different results than those testing with random reads and writes. Internally, our team has benchmarked performance to be anywhere from 3X the performance of a hard drive to less than a standard hard drive. Proceed with caution when someone throws numbers at you."

As for shock resistance, Kohut reports that SSDs are six times more shock resistant than normal hard disks.

Blog Posting Part 2

Six months after his initial posting, Matt Kohut wrote Solid State Hard Disk Drives (SSDs) Part 2 (March 2008) This posting too, is a recommended read.

It seems that Lenovo was practicing Defensive Computing regarding Solid State Hard Disks:

"SSD technology is new. It is undergoing growing pains, and while Lenovo took a lot of heat from our customers for waiting so long to ship an SSD option, we did this for one primary reason. IT'S YOUR DATA and it requires a lot of care to keep it safe. Anything that replaces a tried and true technology for something new should be approached with skepticism until it has proven its worth in the marketplace and has been tested, retested and tested again."

Reporting again on tests by Lenovo engineers, Kohut says:

"Over the time our engineers have been evaluating SSDs, they have learned a lot about what makes a good drive vs. an average drive. All SSDs are not the same and anyone who is evaluating them should do extensive testing. Lenovo testing has shown that some drives from even name brand manufacturers are considerably slower than hard disk drives, especially when writing data. Others are significantly faster for random read operations. Even in a manufacturer's own line, there can be significant differences in performance."

He revisits the interface issue and notes that native SATA interfaces are on the market and he highly recommends them over older SSDs that packaged a parallel drive with a SATA bridge chip. As for power consumption, Kohut says that while all SSDs save on laptop battery life, their power consumption varies, with native SATA drives being the best.

The highlight of this posting, at least for me, is the comparison between the SSD in the Macbook Air and that in Lenovo's ThinkPad X300. The X300 uses a second generation SSD, the Samsung's RBX. Quoting:

"The MacBook Air uses Samsung's older N880X drive. While both are currently shipping 64GB-capacity Samsung drives, the NBX drive that Lenovo uses is 2X+ faster. It has had more growing pains (bugs) worked out of it. It uses SATA technology instead of older Parallel technology with a SATA bridge chip. Compare the ThinkPad X300 with the MacBook Air if you must, but at least give us credit for using a more advanced HDD technology."

Sure enough, the tech specs for the MacBook Air simply refer to a "64GB solid-state drive" and offer no further details. Finally, some ammunition for John Hodgeman. :-)

Ending on a Defensive Computing note, Kohut points out that the worst case scenario with SSDs is much worse than the worst case scenario with traditional hard disks. By worst case, I'm referring to a hardware failure of the disk drive that cuts you off from the only copy of important files.

With traditional hard disks, this may cost you a couple thousand dollars, but there is an excellent chance the data can be recovered. With SSDs however Kohut says "Today if an SSD drive fails, there is currently no commercially available way to get that data back. Anyone using an SSD drive MUST have backups."

I will have more to say about backing up your computer.

See a summary of all my Defensive Computing postings.

[Imalittleteapot]

I think this goes a little too far. In the article it says, "Because SSDs use flash ram to store data, there is no risk of mechanical failure." Really? Absolutely NO risk whatsoever? That's just word play. Haven't you ever broken something with no moving parts? I've broken modems, motherboards, network cards, cell phones, and even OMG?USB sticks with no moving parts! A friend even tripped at a party and put a giant hole in his wall. If there was ever something that doesn't move, it's a wall. Just because it has no moving parts doesn't mean it can't fail. To use the word mechanical to say there is no chance of "mechanical failure" is just asinine. It'll give some people the wrong impression, and they won't do their BACKUPS! Not that I'm against the benefits of an SSD, but IT WILL STILL FAIL! It might not be a "mechanical failure," but I'll bet money when you lose your data that won't make you feel any better. I seriously don't know what people are doing to their computers anyway. I haven't actually fixed a computer, either mine or a friend's, because of HD failure in over fifteen years. It isn't because they don't fail. It's because by the time they do most have a new computer anyway. If they fail prior to that then they were either defective from the factory or you are abusing your computer. Now as for SSDs being faster. Well how fast can I transfer 750 gigs of data to an SSD? The fact that I'll have to wait a year or so before they make an SSD that will hold that much, and the fact that I probably wouldn't be able to afford it for another year or two anyway actually makes an SSD a very slow form of storage don't you think?

[harveybook]

I greatly enjoyed reading this and could not disagree more with the prior comment. I don't understand the comment especially because Michael discusses failure and quotes that data cannot be recovered after an SSD drive fails. The article was very informative on an important issue in which I now have current knowledge of the technology and its problems.

[Imalittleteapot]

That's the whole point. These companies say there's no risk of mechanical failure at the start, and then later we find out it can still fail. Saying there is no risk of mechanical failure is just marketting speak for it fails less often, or if it does fail it will fail some other way. The danger is the average computer user that only reads the first part of the article or only the marketing terms printed on the box. A new user could get confused by this and not understand they still need to backup their data. Even with regular drives it is already hard enough to convince people to backup their data. We should use every chance to remind people to backup regardless of what technology they are using. Also, once you understand it can still fail and you still need to backup your stuff then maybe SSDs aren't all that attractive for the price anymore. Maybe it is better to buy a cheaper drive knowing that if it does fail it can be easily replaced. As long as someone knows the risks they can buy whatever they want. I don't agree with some of the misleading terms people have been using to push these drives.

[mhinnewyork]

I will have more to say about the physical failures of SSDs in an upcoming posting. You are, of course, correct that they can and do fail but the failure isn't mechanical in nature. So walking around the room with an SSD based laptop while its running isn't risky, whereas it is for a traditional hard disk - and the reason is the mechanical nature of the hard disk. As for backup, there too I have much more to say, including, as you point out, the need to have multiple backups on multiple media. To a techie, this goes without saying, I hope to convince non-techies too. Michael Horowitz