Regarding section 5.3 of this paper (section titled 'Data Safety') http://www.usenix.org/events/osdi06/tech/full_papers/weil/weil_html/ I've had some discussions recently about what kind of data consistency we can achieve. >From discussions on this list/IRC, it's clear that right now ceph, with a reasonable crushmap, requires an on-disk write to each of two nodes (either a journal or fs write is acceptable) before returning a write completion. The referred section suggests that there may be a way to have a client notified of a write-to-cache-completion instead when the written data is cached on two nodes (but not yet committed to disk) via the 'ack'. If these acks aren't exposed/used at the ceph layer, are they exposed via librbd, libceph, or librados? -- 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
