Hi, Le 21/10/2014 01:10, 池信泽 a écrit : > Thanks. > > Another reason is the checksum in the attr of object used for deep > scrub in EC pools should be computed when modify the object. When > supporting the random write, We should caculate the whole object for > checksum, even if there is a bit modified. If only supporting append > write, We can get the checksum based on the previously checksum and > the append date which is more quickly. > > Am I right?
>From what I understand, the deep scrub doesn't use a Ceph checksum but compares data between OSDs (and probably use a "majority wins" rule for repair). If you are using Btrfs it will report an I/O error because it uses an internal checksum by default which will force Ceph to use other OSDs for repair. I'd be glad to be proven wrong on this subject though. Best regards, Lionel Bouton
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