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Anu Engineer commented on HADOOP-13738: --------------------------------------- [~arpitagarwal] Thank you for these improvements. I am sure that these are going to make detecting errors on datanode much easier. Had some minor comments / questions. # Not sure what diskchecker.random buys us versus diskchecker.1, diskchecker.2 or diskchecker.3. These files are always deleted after use and in a failure case seeing the sequence number of diskchecker files might be helpful. so I am not sure why we need random at all here. # As [~kihwal] said, just wanted to think though the failure. I can think of 3 distinct failure cases. ## Not able to create a file at all -- You can try 3 times and come out, may be as [~kihwal] said it will take us 6 mins to get out. ## Creation works, but I/O and delete fails -- In this case disk I/O failure is propagated but the junk files remain. Since disk checker will flag the disk is having an issue this case is not problematic. ## File creation and I/O works, but delete fails. We seem to be using {{FileUtils.deleteQuietly}}, shouldn't diskchecker be able to understand the delete operation failed ? Also in this scenario, if we have both random files and delete failures, we might create way too many junk files. If you use dc.1, dc.2, dc.3 -- we might be able to restrict junk files to 3 > DiskChecker should perform some disk IO > --------------------------------------- > > Key: HADOOP-13738 > URL: https://issues.apache.org/jira/browse/HADOOP-13738 > Project: Hadoop Common > Issue Type: Improvement > Reporter: Arpit Agarwal > Assignee: Arpit Agarwal > Attachments: HADOOP-13738.01.patch, HADOOP-13738.02.patch, > HADOOP-13738.03.patch > > > DiskChecker can fail to detect total disk/controller failures indefinitely. > We have seen this in real clusters. DiskChecker performs simple > permissions-based checks on directories which do not guarantee that any disk > IO will be attempted. > A simple improvement is to write some data and flush it to the disk. -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org