Zooko’s weblog entries for yesterday and today reminded me of a link that I, in turn, have had occasion to mention to many people in the past. The Ram I/O project at UMich is intended to be just the sort of crash-resistant memory that Zooko talks about. Their belief, explained in their paper and slides, is that power loss is that the real danger of losing in-memory buffers comes not from power loss – which is trivially addressable with a cheap UPS – but from things the OS (or BIOS, boot ROM, whatever) does to trash memory when it comes up. Accordingly, they designed the Rio File Cache to ensure that the memory containing unflushed disk buffers was in fact preserved through the boot cycle. The numbers they provide, both about failure probabilities and the performance implications of their work, should be food for thought.