Half a Terabyte, Hold the Gravy

What do you do when you've got a device that creates very valuable 2MB files with the press of a button, an action that you may repeat up to 600 times an hour (maybe 20GB a week)? You end up buying another device, such as this puppy: the 500GB Lacie D2 HD Quadra 7200RPM 16MB external drive. I had never before heard of LaCIE, a French concern, but this drive seemed to fit the bill as a backup device. It has a reasonable dollars per gigabyte number, the reviews seemed encouraging, and I went ahead and paid the extra $60 to get the Firewire-capable model as this seems to be recommended over USB for sustained reads and writes typical of an external drive.

PriceGrabber got me thinking about the whole backup plan from the dollars per gigabyte angle for different types of storage devices, summarized here:

Tech	Sample Product	Price w/ S&H	Capacity	$/GB
DVD-R	Verbatim DVD-R 16x 100-pack	$42.27	470GB	$0.09/GB
external HD	500GB Lacie D2 HD Quadra 7200RPM 16MB	$182.60	500 GB	$0.36/GB
flash memory	PNY 4GB USB flash drive	$31.89	4 GB	$7.97/GB

DVD's are an economical choice as a backup medium, especially in my case where making modifications is not important. The 100 disk spindle is almost a direct comparison to the LaCIE drive in terms of capacity, since the LaCIE's actual capacity is more like 460GB. The external drive has the advantage that you don't need find the right disk when you need to retrieve your backup, so it is a good "live" backup solution. The external drive also gives you a little bit of portability, and the model I bought has four connection technologies (hence the name "Quadra") giving some flexibility in working with other devices.

The USB flash drive, on the other hand, is a terrible choice for long term storage, as far as I can tell. That salesman at the electronics store certainly had a lot of nerve trying to talk my Dad out of buying blank CDs in favor of buying a flash drive. The advantage of flash drives is portability, not economics. They weren't looking much cheaper than $8 a gigabyte on PriceGrabber for 1GB and up.

I've left out some options here which I didn't research as much. I've left out the venerable tape backup as well as internal hard drives and NAS. Internal hard drives in a RAID might be a good alternative to the single external drive because you get some automatic failure detection. And the NAS, or Network Attached Storage, goes one better in simplicity.

For this exercise, I've included in my personal backup plan ditching the idea of an "archive quality" medium such as tape in favor of any storage medium which has a long enough life to copy the data onto something newer.

Another idea is to build layers of redundance; one backup is not good enough, and maybe not even two. Somewhere in the back of my head in all this is my dear Grandma's judgment of disgust at the idea of computers, where you can erase everything at the press of a button. This information vulnerability is certainly an Achille's Heel of computing, and it's been an interesting exercise to price out and plan a moderately serious backup system. I'm certainly a novice to this, so if you have some experience to share, I'm all ears.

Quick Thoughts: Programming Productivity

I was thinking hard yesterday about which languages let you be more productive. I'd like to say functional languages let you be more productive. It seemed that it would be so nice to have a few studies done on this, some clinical trials on Scala the wonder drug if you will, with comparisons to languages which have a high placebo effect (they make you think you're writing a program when really you're just creating more work for everyone).

Just now I connected that thought with an earlier one: software is difficult to estimate because it's always the creation of something that has never been done before (even when you're writing a rip-off of an existing program). I reckon that the more unknowns you have, the more risk that your initial estimates will be wrong.

The connection between these two ideas is that it's hard to judge the productivity of a programming language when the utility of the language is to write things that have never been done before. You really do have to actually use and test it in practice. Hence it seems especially useless to have online debates about the productivity of languages without trying them out. It's a little like trying to predict the time performance of a piece of code by examining its source; you really need to actually run it.

For further reading, see Ian Chai's doctoral thesis on documenting object-oriented frameworks (Ian studied under Gang of Four member Ralph Johnson), where he conducted experiments with human subjects to compare how successful different types of documentation were on training someone to use a new framework. It's the only research I know of (not that I'm an expert) where a psychology-esque experiment has been done to test for productivity of a software environment.

Update: added parenthetical remark identifying Ian's advisor.