Raspberry Pi write cycles

I did have a case where the Pi I was using as secondary DNS/DHCP and as the secondary backup server (using USB spinning disk) destroyed its SD card. But then it turned out not to be the load at all. No matter what I ran on that Pi, it would corrupt its SD cards in a matter of weeks (the symptom was that the fourth bit of some bytes would just stick on). I assume it was just something broken in the Pi itself. I will state here, for the record, that if someone can spam effectively -- or be a botnet C&C node -- from TOPS/10 on a PDP-10 emulated on my Pi, my irritation at having my systems abused will probably be overwhelmed by my admiration at their dedication. (Traffic encryption via simh is incredibly painful. You have to turn login delay waaaaay up to run NetBSD on VAX on a Pi if you want to be able to ssh into it; the machine itself runs fine-ish, but the zillions of cycles to encrypt the traffic swamps it in no time.) And, you know, if you manage to cause my SD cards in those machines to fail, well, gosh, guess I'm out $10 or so for a new one. I'm not bothering to back up any of the stuff inside 'em, btw (so those of you using 'em, seriously, save your work elsewhere if it's precious--and, um, yeah, unless you're on OpenVMS, TOPS-20, or ITS, you don't have a TCP/IP stack and since you don't have a direct terminal interface into it, that probably means copying and pasting from the terminal session...but if you have something you really want off it that's larger than a couple of screens full, just write me a note and I can likely extract it for you more reasonably). Adam