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Ben Roling commented on HADOOP-15625: ------------------------------------- bq. BTW, looking @ amazon snowball docs. They only serve up etags from files uploaded with MPU Interesting. Sounds like something to add to documentation with regard to using S3AFileSystem over top of a snowball? I guess it looks like S3AFileSystem over top of snowball doesn't really work at the moment anyway per HADOOP-14710. Another question this raises is whether or not data imported into S3 from snowball can make its way into the real S3 without an eTag. I would hope/guess that an eTag is generated on the transfer from the snowball into the real S3, but I don't have any direct evidence of that. > S3A input stream to use etags to detect changed source files > ------------------------------------------------------------ > > Key: HADOOP-15625 > URL: https://issues.apache.org/jira/browse/HADOOP-15625 > Project: Hadoop Common > Issue Type: Sub-task > Components: fs/s3 > Affects Versions: 3.2.0 > Reporter: Brahma Reddy Battula > Assignee: Brahma Reddy Battula > Priority: Major > Attachments: HADOOP--15625-006.patch, HADOOP-15625-001.patch, > HADOOP-15625-002.patch, HADOOP-15625-003.patch, HADOOP-15625-004.patch, > HADOOP-15625-005.patch, HADOOP-15625-006.patch, HADOOP-15625-007.patch, > HADOOP-15625-008.patch, HADOOP-15625-009.patch, HADOOP-15625-010.patch, > HADOOP-15625-011.patch, HADOOP-15625-012.patch > > > S3A input stream doesn't handle changing source files any better than the > other cloud store connectors. Specifically: it doesn't noticed it has > changed, caches the length from startup, and whenever a seek triggers a new > GET, you may get one of: old data, new data, and even perhaps go from new > data to old data due to eventual consistency. > We can't do anything to stop this, but we could detect changes by > # caching the etag of the first HEAD/GET (we don't get that HEAD on open with > S3Guard, BTW) > # on future GET requests, verify the etag of the response > # raise an IOE if the remote file changed during the read. > It's a more dramatic failure, but it stops changes silently corrupting things. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org