Tuesday, January 29, 2008

Odd Solaris DiskSuite problem, and solution

One of the systems I admin had a failed disk that was in use by two DiskSuite RAID 5 volumes (IMO insane, given the performance hit, but not my decision). After the disk was replaced, any attempt to run DiskSuite programs such as 'metastat' gave the following error:

Assertion failed: mdrcp->colnamep->start_blk <= rcp->un_orig_devstart, file ../common/meta_raid.c, line 151
metastat: Abort
Abort (core dumped)

No documentation about this error available anywhere, and a Google only found 3 or 4 hits, none of them helpful (one of them involved using LD_PRELOAD to replace the abort() function to allow 'metaclear' to delete the RAID, recreate it, and reload from backups.

I worked out why the error occurred, though. When the disk was replaced, it of course came with a label/TOC with partitions defined. If these partitions don't match the pre-existing RAID setup, the metadisk tools die a death.

All that was required was to build up the proper partitioning, and then everything worked fine.

Wednesday, January 9, 2008

Learning things by writing for Wikipedia

I love learning new things, and always have; I find that writing for Wikipedia is a great way to do that. All the talk about experts often misses the point; articles for a general audience are often best written by a reasonably knowledgable non-expert referring to works by experts. To the expert, it's all obvious, and the true insights are often not already published. Since we want everything to be referenced on Wikipedia and hopefully readable by an intelligent individual not very knowledgable on the subject matter but willing to do a little background reading.

So this week, I've started a few articles, one of which is [[du Bousquet locomotive]], about a rather obscure French design of articulated steam locomotive. I'd vaguely heard of them before, had seen a picture or two and thought them odd-looking, and paid them no further thought.

Then I got to searching Google Books for out-of-copyright stuff about steam locomotives (a favorite pastime; it's amazing how much stuff is out there now, scanned in from university libraries) and came across a photo in an old issue of Cassier's Magazine - an around the turn of the century illustrated magazine on engineering, mostly transportation and electrical engineering. Wikipedia needs an article on it, but that'll keep till later.

This piqued my interest and got me to researching. I found some stuff on the web, a little in recent books, and some more in Google Books, and started an article. Turns out that three different French railway systems had them, one system being almost undocumented on Wikipedia (the Grand Ceinture of Paris; hey, another article to research and write!) as well as two foreign railways; one in Andalusia in Spain, and another in China. Neither of which railway system appears to have a Wikipedia article.

Four new article ideas, not including the one I've just worked on; five, in fact, given that the designer, Gaston du Bousquet, also lacked an article. I knocked up a quick stub based on the French Wikipedia's article on him, and intend to expand it. He died in 1910, so I expect there'll be some obituaries out there in out-of-copyright land that I can easily find.

Researching any topic like this gives the lie to the idea some people have that with two million or so articles, surely everything is documented but 'cruft'? Unless one arrogantly thinks that if a young computer nerd doesn't know of it, it doesn't matter, of course. Obscure history and historical technology doesn't appear to be regularly a deletionist target, fortunately.

Instead, researching one topic finds half-a-dozen undocumented new topics, and each of those will find more, a whole growing tree of knowledge to nurture.

That's exactly why I do it.

Starting a new blog ...

I know - I've done it before. This is far from my only blog, but the others were rather subject-specific; one on photography, one on railways, etc etc. I found myself wanting to write things but finding that it really didn't fit the format of my existing blogs. So, with no apologies, something a bit more generalist.

One subject that will come up is Wikipedia, a project I'm highly involved in.