Hey, I'm trying to replicate Flashield for a filesystem with bcache: * https://www.usenix.org/conference/nsdi19/presentation/eisenman I have a filesystem on SSD with lots of tiny cache files and my goal is to: * Not write files that are going to be overwritten (low TTL for example) * If I end up writing, I want to write in large chunks to reduce write amplification These two things combined should greatly reduce durability requirements for SSD. Is it possible to achieve with bcache? I can live without durability. So far I've tried: * Storage on SSD * Cache on /dev/ram0 * Disabled sequential cutoff * Enabled writeback * Put ext4 without a journal on /dev/bache0 But it seems like some writes still spill directly onto durable storage, dd of 10MB of zeros reliably generates IO almost immediately (before writeback delay), which I am trying to avoid in the first place. I have a fuse implementation of what I want to do, but was hoping to get away with what is available out of the box. Thanks!
