Solid State Hard Disk Drives (SSDs) Part 2

I'm not one to defend a competitor here, but I highly doubt that any Tier One vendor is seeing SSD hard disk drives being returned at a 10 percent rate. The article circling the Internet is fear mongering meant to drive readership. On the other hand I do doubt that return rates are as low as traditional hard disk drives though. For those that aren't familiar with what I'm talking about, there are stories and blog posts that suggest that "a leading vendor" has had major issues with solid state hard disk drives including premature failure and poor performance that isn't meeting customer expectations. Here's one example. I've written about SSD drives before and it probably warrants an update. Like in the last post, I'm indebted to Jeff Hobbet and the other engineering teams here at Lenovo. Many of the words here are theirs. Getting to work with these guys on a regular basis is one of the highlights of my job. 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. (The same can be said for just about anything from Full Encrypting HDDs to LASIK surgery). As the SSD industry grows, manufacturers are wrestling with many problems like:

Endurance– or how many times a cell inside an SSD drive can be erased and rewritten before it goes bad (i.e. cannot maintain an electrical charge). Hard disk drives have no practical physical limit in this area.

Data retention– though SSD drives use solid state technology, they DO wear out. The more times they are written to and erased, the less time they can maintain data in storage. Hard disk drives can reliably maintain data for ten years or so regardless of how much they are used. SSD drives, depending on their usage pattern, can also have data retention times up to ten years. In practical usage, this often will be considerably less. The more you use it, the less time an SSD can retain your data. Thus, these drives SHOULD NOT be used for archival storage. The industry has come up with some clever ways of making drives last as long as possible. Your average 64GB SSD drive actually contains more like 68GB of flash memory. The extra is used by the SSD to automatically be a reserve for those cells that wear out. Additionally the drive is using wear leveling algorithms to constantly move the data around internally to prevent hot spots from wearing out prematurely. Lenovo engineers have set a design target of a write throughput which we know to be well above what the average user will experience over the lifetime of his or her machine. Our engineers have the data that show that the 2nd generation Samsung SSD drive that Lenovo uses (the Samsung RBX – more on that later) will perform to those standards or better.

Performance – 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. For example, I mentioned that Lenovo uses Samsung's RBX drive. 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. Better yet, run benchmarks and see for yourself. Our advice is to test SSDs with the applications you use most often, including your email client and other programs you use on a regular basis. For today, yeah go ahead and look for a single level cell (SLC) instead of a multi level cell (MLC) drive. But honestly if you buy from a name brand manufacturer, it is likely going to be an SLC drive anyway. Plus, as the industry advances, there are going to be implementations of multi level cells arrayed in parallel to deliver single level cell performance, so SLC technology alone won't always be a good determinant of performance. Also ask if the drive is a native SATA implementation or a parallel drive with a SATA bridge chip. You want the native SATA implementation. They're better in all aspects.

Power Consumption – All SSDs are going to save you battery life on your notebook, but some will save you more than others. Again, the native SATA drives will give you better battery life.

Failures – Worst case if a spinning platter HDD fails, there are clean room services that can open it up and read the data. 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. It is this reality that has prevented them from being widely deployed in the corporate world. (Yes, high cost too.) All in all, Lenovo is bullish on SSD drives and their potential. We think that the drives shipping in our products meet all customer requirements for performance, durability, and will live up to their claims. But don't just buy because it is new. Do your homework.