Hi everyone. I'm new here and interested in the CRUSH algorithm which is a part of Ceph, so I'm just reading the paper from http://ssrc.ucsc.edu/Papers/weil-sc06.pdf Unfortunately I'm not native English speaker, so I do have some problem understanding the content. I wish anybody here could help. I encounter the word "decluster" which cannot be found in a dictionary. I think it should have something to do with "cluster", but I'm not able to tell the actual meaning of it. Appearance: page 1 Further, existing randomized distribution schemes that decluster replication by spreading each disk’s replicas across many other devices suffer from a high probability of data loss from coincident device failures. Appearance: page 2 We say that CRUSH generates a declustered distribution of replicas in that the set of devices sharing replicas for one item also appears to be independent of all other items. 2. I don't understand "per-device weight value" Appearance: page 2 The CRUSH algorithm distributes data objects among storage devices according to a per-device weight value, approximating a uniform probability distribution. 3. What does the word "metric" mean? Appearance: page 3 This results in a one-dimensional placement metric, weight, which should be derived from the device’s capabilities. It seems slow that I can go through only 1 page per day averagely. -- 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
