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December 21, 2014
Storage wars
Anyone who's ever watched the "Storage Wars" reality TV series on the A&E Network knows that with storage, you never know what you're going to get. That's true for stuff people stow away in storage units, and it's also increasingly true with the kind of storage in our electronic devices.
There was a time when RAM was RAM and disk was disk, and for the most part the only rule was that more was better. But that was in the era when you could count the total number of available Intel processors on the fingers of a hand or two instead of the roughly one thousand they offer now.
These days things are much more complicated. And just as often no one seems to quite know for sure why a certain processor was chosen for a particular product, there aren't easy answers why a product uses this type of storage versus that. There often appears to be a disconnected between the engineers that make those often arcane decisions and the marketing side of things that must explain what it's for and why it's better.
Here are a couple of examples we've recently come across:
DDR3L vs. LPDDR3 — In mobile computing devices designed to draw as little power as possible you generally not only find "low power" processors (where low power refers to the low amount of electricity use, not the chip's performance), but also DDR3L random access memory. In the case of DDR3L, the L stands for a lower voltage version of the DDR3 memory standard, and more specifically 1.35 Volts instead of the standard 1.5 Volts. That kind of makes sense.
However, you now increasingly also see devices with LPDDR3 RAM, especially in handhelds and tablets. LPDDR3, it seems, was created specifically for such devices, and their need to be able to go into standby modes where the memory uses as little power as possible. LPDDR3 runs on 1.2 Volts, is part of the main board, and generally uses only about a tenth as much power while in standby as does regular DDR3 RAM.
Initially I thought LPDDR3 was a lower cost type of memory as we first saw it in lower cost units. But apparently its cost is actually higher than that of standard of even low power DDR3. And it's used in high-end devices such as the Apple MacBook Air.
SSD vs. eMMC — We've long been seeing substantial differences in benchmark performance between different types of solid state storage. There's generally not much of a difference between the performance of different rotating media, a large difference between solid state storage and rotating media (solid state is much faster), and a very large difference between different types of solid state storage.
Recently we observed an almost 10:1 difference between the SSD and eMMC mass storage performance in two tablets of roughly the same size, one low end and one higher end. SSD stands for Solid State Disk, eMMC for embedded Multi Media Card. The generic difference between the two, apart from a great variance of flash memory speed itself, is the sophistication and complexity of the controller and interface. eMMC have a basic controller and a relatively slow interface, whereas SSDs use complex controllers and one of the various SATA interfaces.
There's always an inherent answer to any tech question, it's just that those answers aren't easy to come by. What I'd like to see more of is how something works, what its pros and cons are, and why it's used in certain products.
Posted by conradb212 at December 21, 2014 4:28 PM