ctrl.altered.mind

A friend asked me for my brief opinion regarding solid-state drives, particularly in the event of actual reviews of these devices pouring in (such as this one by Walt Mossberg of the Wall Street Journal). For the uninitiated, these solid-state drives are drop-in replacements for conventional hard disc drives (or HDDs), but employ flash storage instead of storing data on rotating magnetic media.

While this technology may be an interesting alternative for some, I do not see SSDs denting the expansive HDD market at least over the next decade. There will be some low storage capacity markets that would be taken over by solid-state storage, such as handhelds and special-purpose laptops. SDDs differ from flash storage employed by portable devices such as digital cameras and music players in two aspects: the type of flash memory used, and the interface. Current generation SDDs use the SATA interface and have a HDD-like form factor; and are therefore designed as a drop-in replacement for conventional hard drives.

My comparative reasoning between SDD and HDD technologies, is as follows:

Conventional hard drives are a mature technology and are continually seeing impressive gains in storage density (due to better materials, advances in physics, and better recording techniques). It is a just a matter of time until we start seeing multiple terabyte storage in hard drives. With a tremendous shift in media consumption towards high-definition audio and video formats, the quantity of available storage will be a perennial question.

While they do involve moving parts, the energy usage to operate a hard drive is a tiny fraction of that used for other computer parts. In todays laptops, powering the screen consumes the most energy, although this is being mitigated by the use of LED backlighting in some newer devices. In fact, in a comparative test recently performed on the Apple Macbook Air by Ars Technica, it was seen that a solid state drive presented no significant benefit in terms of battery life, even in an LED-backlit laptop computer.

The data access time benefit from flash storage is usually mentioned, but there are two sides to this story. Flash beats HDDs when it comes to random access times (due to spin delays in HDDs). However, HDDs have far superior sequential access times than SDD storage, which is of great importance in video playback and retrieving of any sequentially placed data. Moreover, with a new breed of hybrid HDDs that employ larger flash memory caches for frequently accessed information, users would be able to benefit from the best of both worlds (with greatly improved random/sequential access times as well as higher storage capacity).

A prime disadvantage of SSDs is the limited number of rewrites to memory. This makes it mandatory to perform wear-leveling within the SSD to prevent repeated rewrites to the same sections. This issue is expected to make recovering lost data from SSDs far more difficult than is the case with HDDs.

So far, the biggest advantage that I see favoring SDDs in portable computers, is the resilience from shock and damage arising from dropping the device. Therefore, computers built for rugged use and/or harsh environments would strongly benefit from using SDDs, if the compromise on storage capacity is acceptable.

The USB Implementers Forum is planning to announce the next generation of the ubiquitous Universal Serial Bus technology by mid 2008. USB 3.0 will allow a ten-fold increase in data transfer rates, by adding fiber-optic links alongside traditional copper wires in the bus - which would boost the specification to a theoretical 4.8 Gigabits per second (the current USB 2.0 version has a top data-transfer rate of 480 megabits per second).

Although not too many external peripherals would be able to make use of such bandwidth, the technology implies a completely different meaning for devices such as external hard drives and next-generation optical drives like Blu-Ray and HD-DVD. The data transfer rate of internal SATA hard drives today caps out at 3 Gbps, with most desktops and laptops using a lesser SATA version that allows only up to 300 Mbps. The prospect of an external hard drive having the ability to exceed transfer rates of today’s internal drives, is very promising - as transfer speeds are the only strong differential that separates the two categories of consumer hard drives today.

There is probably no need to hold off on that impending hard drive purchase just yet, as USB 3.0 products won’t be arriving in the marketplace before 2009 or 2010.

(via slashdot)

In Issue 134 of The Embedded Muse, editor Jack Ganssle writes:

I have a beef with many college computer science departments. If one
wanted to be a great novelist the English Department would require
that this person knew how to read, and would have insured he’d read
many great novels before starting one of his own. The Music
Department would assume an aspiring composer had listened to lots and
lots of music, and read many scores. Yet CS Departments take a
different tack: Here’s how a for loop works. Your assignment: write
some code. As a result most graduates are forced to invent their own
styles and adopt some half-baked (if any) process.

Programming students should read great code. A lot of it.
Professional developers should read great code. A lot of it. We can
and must be constantly learning.

Read the rest of this entry »