ImperialViolet

Hardware Hell (01 Sep 2002)

It has a really bad few days for hardware. Firstly, metis (the server which hosts IV) dropped off the face of the net sometime Friday. As I write this it's still down, but I'll be going in to see what died tomorrow. Hopefully it just hit its mean time between failure for the memory and a bad bit flip killed it. Then again, another rat may have pissed in the power supply and shorted it out (I kid you not - that's what killed it last time)

Talking of PSUs I think I need a new one. Twice today my SCSI array failed which causes a reasonably slow, but always fatal, system failure as more and more processes get stuck in the escalator. I'm pretty sure that I'm browning out the power supply having in my case, as I do:

Time for a bigger PSU I think

Math's Gem

Ok, so I'm sure it's a really well known result in number theory, but it's the first time I've seen it:

For any integer n, to find the number of factors of the integer find the exponents of the primes in its prime factorisation (call that set a) and eval (reduce #'* (mapcar (lambda (x) (+ x 1)) a)))

For example: where n=12 the prime factorisation is 2^2, 3^1 so a=(2, 1) and it has (2 + 1)(1 + 1) = 6 factors (namely 1,2,3,4,6,12)

Comments

It's a pretty standard feature of most blogs that users can add comments. Well, IV has never had that because it would require PHP (or something similar) and I just don't trust apache/PHP to be secure. However, after a remark from Ian I thought that I might be able to have an email based comment system. Watch this space.

Static analysis of code

I mentioned on Friday that statically analysing untrusted machine code to prove that it's safe to run might be a good idea (go read the post if you haven't already). Well, having thought about it (and looked at RTL) I'm thinking that working with C code might not be so bad after all. I've found a library (CTool) that looks as if it will make the whole parsing a lot easier. Again, watch this space.