Thanks very much for your help, and please see my inline comments/questions.
On Thu, Nov 7, 2013 at 2:30 AM, Samuel Merritt <s...@swiftstack.com> wrote: > On 11/6/13 7:12 AM, Daniel Li wrote: > >> Hi, >> I have a question about swift: what does swift do if the auditor >> find that all 3 replicas are corrupt? >> will it notify the owner of the object(email to the account owner)? >> what will happen if the GET request to the corrupted object? >> will it return a special error telling that all the replicas are >> corrupted? >> Or will it just say that the object is not exist? >> Or it just return one of the corrupted replica? >> Or something else? >> > > If all 3 (or N) replicas are corrupt, then the auditors will eventually > quarantine all of them, and subsequent GET requests will receive 404 > responses. > No notifications are sent, nor is it really feasible to start sending them. > "The auditor" is not a single process; there is one Swift auditor process > running on each node in a cluster. Therefore, when an object is > quarantined, there's no way for its auditor to know if the other copies are > okay or not. > > Note that this is highly unlikely to ever happen, at least with the > default of 3 replicas. When an auditor finds a corrupt object, it > quarantines it (moves it to a "quarantines" directory). Did you mean that when the auditor found the corruption, it did not copy good replica from other object server to overwrite the corrupted one, it just moved it to a quarantines directory? Then, since that object is missing, the replication processes will recreate > the object by copying it from a node with a good copy. When did the replication processes recreated the object by copying it from a node with a good copy? Does the auditor send a message to replication so the replication will do the copy immediately? And what is a 'good' copy? Does the good copy's MD5 value is checked before copying? > You'd need to have all replicas become corrupt within a very short > timespan so that the replicators don't get a chance to replace the damaged > ones. > > _______________________________________________ > OpenStack-dev mailing list > OpenStack-dev@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >
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