On Fri, Jun 29, 2012 at 11:42 AM, Brian Edmonds <mornir@xxxxxxxxx> wrote: > What are the likely and worst case scenarios if the OSD journal were > to simply be on a garden variety ramdisk, no battery backing? In the > case of a single node losing power, and thus losing some data, surely > Ceph can recognize this, and handle it through normal redundancy? I > could see it being an issue if the whole cluster lost power at once. > Anything I'm missing? If you lose a journal, you lose the OSD. The end. We could potentially recover much of the data through developer-driven manual data inspection, but I suspect it's roughly equivalent to what a lot of data forensics services offer — expensive for everybody and not something to rely on. Ceph can certainly handle losing *one* OSD, but if you have a correlated failure of more than one, you're almost certain to lose data some amount of data (how much depends on how many OSDs you have, and how you've replicated that data). If that's an acceptable tradeoff for you, go for it...but I doubt that it is when you come down to it. -Greg -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
