[ https://issues.apache.org/jira/browse/HDFS-4015?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Anu Engineer updated HDFS-4015: ------------------------------- Attachment: (was: HDFS-4015.002.patch) > Safemode should count and report orphaned blocks > ------------------------------------------------ > > Key: HDFS-4015 > URL: https://issues.apache.org/jira/browse/HDFS-4015 > Project: Hadoop HDFS > Issue Type: Improvement > Components: namenode > Affects Versions: 3.0.0 > Reporter: Todd Lipcon > Assignee: Anu Engineer > Attachments: HDFS-4015.001.patch > > > The safemode status currently reports the number of unique reported blocks > compared to the total number of blocks referenced by the namespace. However, > it does not report the inverse: blocks which are reported by datanodes but > not referenced by the namespace. > In the case that an admin accidentally starts up from an old image, this can > be confusing: safemode and fsck will show "corrupt files", which are the > files which actually have been deleted but got resurrected by restarting from > the old image. This will convince them that they can safely force leave > safemode and remove these files -- after all, they know that those files > should really have been deleted. However, they're not aware that leaving > safemode will also unrecoverably delete a bunch of other block files which > have been orphaned due to the namespace rollback. > I'd like to consider reporting something like: "900000 of expected 1000000 > blocks have been reported. Additionally, 10000 blocks have been reported > which do not correspond to any file in the namespace. Forcing exit of > safemode will unrecoverably remove those data blocks" > Whether this statistic is also used for some kind of "inverse safe mode" is > the logical next step, but just reporting it as a warning seems easy enough > to accomplish and worth doing. -- This message was sent by Atlassian JIRA (v6.3.4#6332)