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Hi William, the reason that after a total init the consumer does not have the latest state of the supplier RUV and is receiving updates based on the RUV at start of the total init is independent of the modrdn problem. When a supplier is performing a total init it is still accepting changes, the total init can take a while and there are scenarios where an entry which is already sent is updated before total init finishes. We cannot loose these changes. Therfor the update resolution/ entry state resolution on the consumer side has to handle this, ignore changes already applied and apply new changes. And it handles it, if there are bugs they have to be fixed. Now, I am no longer sure if the fix for 48755 handles correctly all modrdns received after the id list was prepared, the parentid might change while the total init is on progress. This brings up my origimal suggestion to handle the modrdn problems also on the consumer side. Ludwig On 06/30/2016 02:34 AM, William Brown
wrote:
Hi, Now that https://fedorahosted.org/389/ticket/48755 is merged, I would like to discuss the way we handle CSN with relation to this master. As I'm not an expert on this topic, I want to get the input of everyone about this. Following this document: http://www.port389.org/docs/389ds/design/changelog-processing-in-repl-state-sending-updates.html As I understand it, after a full online init, the replica that consumed the changes does not set it's CSN to match the CSN of the master that sent the changes. As a result, after the online init, this causes a number of changes to be replicated from the sending master to the consumer. These are ignored by the URP, and we continue. However, in a number of cases these are *not* ignored, and have caused us some bugs in replication in the past. We also have some failing changes that are skipped, which could in certain circumstance lead to inconsistency in replicas. We have gone to a lot of effort to be able to skip changes, to handle the case above. The reason was is that if there was a modrdn performed, and the entry ID of the entry that was moved was less than the new parent ID, this *had* to be skipped, so that after the online init the modrdn change was replayed and applied to the consumer. Since 48755 which sorts based on the parent ID, this seems to no longer be an issue. So we don't need to have the master replay it's changelog out to the consumer, because the consumer is now a literal clone of the data. So, is there a reason for us to leave the CSN of the consumer low to allow this replay to occur? Or can we alter the behaviour of the consumer to set it's CSN to the CSN of the sending master, so that we don't need to replay these changes? -- Red Hat GmbH, http://www.de.redhat.com/, Registered seat: Grasbrunn, Commercial register: Amtsgericht Muenchen, HRB 153243, Managing Directors: Charles Cachera, Michael Cunningham, Michael O'Neill, Eric Shander |
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