Hi Kyle, Loic, The current code uses a “FIT rate multiplier” to include for instance the effect of operations done in parallel. That multiplier (n) has an effect on Pfail. In the initial failure, it is calculated using the number of replicas and the stripe count as seen in https://github.com/ceph/ceph-tools/blob/master/models/reliability/RadosRely.py#L86. The thing that doesn’t have sense to me is the way the multiplier is calculated for the failure of the remaining copies in https://github.com/ceph/ceph-tools/blob/master/models/reliability/RadosRely.py#L92 Why the stripes are not taking into account? What is the purpose of using the “declustering factor” on that equation? Is that equation correct? I read this note by sage https://www.mail-archive.com/ceph-devel@xxxxxxxxxxxxxxx/msg01650.html trying to clarify the role of PGs but didn’t help me to understand it. Besides, I have a simple question related with the equation on L86 for the initial failure. The stripping process splits user content in #number of objects, which equivalent to the stripe count. That group of objects constitutes an object set. Each object is composed by one or more stripes units. All stripes units (stripe count) are written in parallel. Typically each object is mapped to a different disk. What happen when the object set is full and a new object is started? Are this new objects assigned to same disks used for the previous full object set? Best koleosfuscus ________________________________________________________________ "My reply is: the software has no known bugs, therefore it has not been updated." Wietse Venema -- 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
