Fri, 29 Apr 2011

The short term fallacy
There are a couple of things that I'm butting my head up against these days that all seem to be aspects of the same general problem, which I mentally label the 'short term fallacy'. This fallacy generally states that there's no point planning for something to survive a long time because if there are legacy problems they can be solved simply by starting again. Examples of this are:

• A building in Brisbane that I worked in - Mineral House - was supposed to have a 25 year lifespan. Components in it were not designed to last a lot longer than that because theoretically the building would be pulled down and rebuilt with a larger, better one later.
• File systems that don't support defragmenting - when you ask about defragmenting the experts say "just blow it away and restore from backups" (or the even better ridiculous statement that "ext3 doesn't fragment").
• Programs that leak memory - even those that are only supposed to be run for a short time.
• Networking people don't want to support IPv6 because it's easier to just add a layer of NAT, using a higher level of DHCP turnover, proxies, or whatever.
• Databases that allow you to add data files to table space, but do not allow you to remove them without destroying any table that used that file, provide no way to migrate used data in that file to other free space elsewhere, or even direct the database to not allocate objects to that file, and little information about what objects might even be in a file.
• People requiring certain older technology - PCs with ISA sockets, for example - in order to support the old RS-422 data adapters, rather than spend the money on rewriting the software to be adapter independent or use more modern equipment.
• Protocols and systems written with no version information, so that version A cannot work out if version B's data is correct or even compatible. This category also includes programs where reading any other version is explicitly denied without any knowledge of what differences those revisions might have made to the data being read or written.
• Programs written with the assumption that no-one else is ever going to need to use your program, so things like documentation, data recovery or error checking don't have to be done.
• Employing a person whose job it is to go through your data warehouse and press the reset button on servers that have hung - and their entire eight hours a day is taken up with this.

Yes, these problems are hard. Yes, limits have to be set - processors will use a certain number of bits for storing a register and so forth. Yes, sometimes it's impossible to predict the things that will change in your system - where your assumptions will be invalidated. But we exist in a world that moves on, changing constantly, and we must acknowledge that there is no way that the system we start with will be the same as the system we end up using. The only thing that's worse than building in limitations is to insert them in such a way that there is no way to upgrade or cope with change. Limitations exist, but preventing change is just stupid.

And the real annoyance here is that there are plenty of examples of other, equivalent systems coping with change perfectly. LVM can move the contents of one disk to another without the user even noticing (let alone having to stop the entire system). Tridge and Rusty have demonstrated several methods of replacing an old daemon with a newer version without even dropping a single packet - even if the old program wasn't designed for it in the first place. File systems that insist that it's impossible to shrink are shown up by file systems with similar performance that, again, can do so without even blocking a single IO. You don't even have to reboot for a kernel upgrade if you're using ksplice (thanks to Russell Coker for reminding me).

It's possible to do; sometimes it's even elegant. I can accept that some things will have a tradeoff - I don't expect the performance of a file system that's being defragmented to be the same as if it was under no extra load. But simply saying "we can't shrink your filesystem" is begging the question "why not", and the answer will reveal where you limited your design. The cost, in the long run, will always be higher to support a legacy system than to future-proof yourself.

posted at: 23:26 | path: /tech/ideas | permanent link to this entry

Edgar Wallace - The Green Rust
I've been reading ePub books on my Samsung Galaxy S almost since I got it, and it's been a Good Thing.

The screen is large enough to read text fairly quickly - a speed reader could easily scan each line in portrait mode without moving their eyes horizontally at all. Yet it's not too large to be uncomfortable to hold. The Alkido reader supplied is adequate but I prefer FBReader - with a nice serif font (although there's little evidence at all for it being more legible, it does render the italics of some of my books correctly - something I'd originally thought had been an error in the book encoding or the reader), its 'night-time' white-on-black mode, and its better organisation of my library.

Mostly the books I've picked up have been from Project Gutenberg, which my readers probably know well. As my views on 'strong' copyright are also fairly well known it would be otiose to relate them, but I see Project Gutenberg as proof that the doomsday scenarios of the 'strong' copyright lobby paint of the time after the copyright in a work expires - that either everyone will be copying it like crazy and making money out of it, or that it will mean obscurity and lack of recognition for the author - are baseless. Project Gutenberg makes these works available for free and by doing so the authors works are preserved and gain value by their availability, but without any one company profiting from the process. In fact, the 'strong' copyright arguments basically devolve to "but we won't be making any money from it", even though often they aren't anyway.

(Message to Disney: there are children growing up now who have no idea what Mickey Mouse is. Deal with it.)

Anyway, one of my finds was The Green Rust by Edgar Wallace, based on having found that two early Agatha Christie novels - The Mysterious Affair at Styles and Secret Adversary - were available, based on having read through A Study in Scarlet and looked up the subject "Detective and mystery stories". I'd link you to that search but for several badly thought-out reasons Project Gutenberg have decided that looking up a subject or author should have no well-formed, static URL.

Now, Edgar Wallace was a name I recognised from a different context. Many years ago Severed Heads released a track called "Dead Eyes Opened", originally released in 1984 but with a new dance remix in 1994 that became their only really mainstream hit. It borrows from Edgar Lustgarten's audio recording of the crime that I later found out was incongruously called The Crumbles Murders. In it, he says:

Then — I owe a debt here to Edgar Wallace, who edited the transcript of the Mahon trial — …

Yes, it's that Edgar Wallace. Not only a famous court reporter but also an author of many fiction novels, mostly detective and mystery stories, and as the part inventor of King Kong. And I have to say that his writing is quite enjoyable - not as old as Doyle's and with a touch of genre-savvy, and with a bit less reveal-everything-at-the-end compared to Christie. It's strange how these little synchronicities in life come about.

posted at: 17:14 | path: /tech | permanent link to this entry

Constantly learning
After I build my tenth Electric Vehicle, I think I'll just start to have a basic knowledge of how to do so.

After all, just today I learnt about the Tritium Wavesculptor, a high-end controller for brushless three-phase DC motors (which aren't really DC motors, they're actually AC, it's just that the simpler controllers just output on-off square-like waves to energise each phase in turn, but that's another story). And they make a battery management system too - one that is actually formed (by chance) for the specific type of cell I have.

I learnt this not in a search for controllers - apart from already having one, I had discovered the EVnetics Soliton One (I refuse to link to EVnetics' site since it's Flash-only, but here's Rebirth Auto selling one for a mere $2,995 USD). Since that was far more controller than I needed - even the Soliton Jr doesn't really work under 240VDC, which is twice my standard pack voltage - I hadn't really looked around for more. I actually noticed a reference to a "Tritium Wavesculptor" in a post on the AEVA forums about converting (of all things) a VW Type 3.

Tritium are an Australian company that's been around and creating EV controllers for, oh, nearly a decade! How is it that I haven't heard of them?

Clearly, this is a field that needs a really good directory of motors, controllers and batteries. And, just as clearly, the market is fragmented - dozens of forums (with names from the normal to the incomprehensible and unguessable), dozens of suppliers, minimal coherence of specification (e.g. some cells are measured in grams per watt hour, some in litres per amp hour, etc.) and dozens, even, of supplier lists and directories on forums, enthusiast and club sites, and elsewhere. I feel the need to create a motor comparison and controller comparison site, if I didn't think I was already struggling for time just to do the things I want to do that are relevant to me right now.

Sigh.

posted at: 17:12 | path: /personal/ebike | permanent link to this entry

All posts licensed under the CC-BY-NC license. Author Paul Wayper.

You can also read this blog as a syndicated RSS feed.