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Date: Mon, 6 Feb 2012 18:39:59 +0000 (UTC)
From: "Jonathan Ellis (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (CASSANDRA-3468) SStable data corruption in
 1.0.x
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    [ https://issues.apache.org/jira/browse/CASSANDRA-3468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13201453#comment-13201453 ] 

Jonathan Ellis commented on CASSANDRA-3468:
-------------------------------------------

Sylvain and MaHaiyang are right, compaction ignores the cache entirely and always reads directly from disk.

We're unable to reproduce using Terry's test harness on our hardware or on EC2.  Given the sha mismatches immediately after write noted by Sylvain, and the lack of a link between compaction to the cache in Cassandra, the evidence overwhelmingly points towards some kind of environmental problem in Terry's cluster.
                
> SStable data corruption in 1.0.x
> --------------------------------
>
>                 Key: CASSANDRA-3468
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3468
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.0.0
>         Environment: RHEL 6 running Cassandra 1.0.x.
>            Reporter: Terry Cumaranatunge
>              Labels: patch
>         Attachments: 3468-assert.txt
>
>
> We have noticed several instances of sstable corruptions in 1.0.x. This has occurred in 1.0.0-rcx and 1.0.0 and 1.0.1. It has happened on multiple nodes and multiple hosts with different disks, so this is the reason the software is suspected at this time. The file system used is XFS, but no resets or any type of failure scenarios have been run to create the problem. We were basically running under load and every so often, we see that the sstable gets corrupted and compaction stops on that node.
> I will attach the relevant sstable files if it lets me do that when I create this ticket.
> ERROR [CompactionExecutor:23] 2011-10-27 11:14:09,309 PrecompactedRow.java (line 119) Skipping row DecoratedKey(128013852116656632841539411062933532114, 37303730303138313533) in /var/lib/cassandra/data/MSA/participants-h-8688-Data.db
> java.io.EOFException
>         at java.io.RandomAccessFile.readFully(RandomAccessFile.java:399)
>         at java.io.RandomAccessFile.readFully(RandomAccessFile.java:377)
>         at org.apache.cassandra.utils.BytesReadTracker.readFully(BytesReadTracker.java:95)
>         at org.apache.cassandra.utils.ByteBufferUtil.read(ByteBufferUtil.java:388)
>         at org.apache.cassandra.utils.ByteBufferUtil.readWithLength(ByteBufferUtil.java:350)
>         at org.apache.cassandra.db.ColumnSerializer.deserialize(ColumnSerializer.java:96)
>         at org.apache.cassandra.db.ColumnSerializer.deserialize(ColumnSerializer.java:36)
>         at org.apache.cassandra.db.ColumnFamilySerializer.deserializeColumns(ColumnFamilySerializer.java:143)
>         at org.apache.cassandra.io.sstable.SSTableIdentityIterator.getColumnFamilyWithColumns(SSTableIdentityIterator.java:231)
>         at org.apache.cassandra.db.compaction.PrecompactedRow.merge(PrecompactedRow.java:115)
>         at org.apache.cassandra.db.compaction.PrecompactedRow.<init>(PrecompactedRow.java:102)
>         at org.apache.cassandra.db.compaction.CompactionController.getCompactedRow(CompactionController.java:127)
>         at org.apache.cassandra.db.compaction.CompactionIterable$Reducer.getReduced(CompactionIterable.java:102)
>         at org.apache.cassandra.db.compaction.CompactionIterable$Reducer.getReduced(CompactionIterable.java:87)
>         at org.apache.cassandra.utils.MergeIterator$ManyToOne.consume(MergeIterator.java:116)
>         at org.apache.cassandra.utils.MergeIterator$ManyToOne.computeNext(MergeIterator.java:99)
>         at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:140)
>         at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:135)
>         at com.google.common.collect.Iterators$7.computeNext(Iterators.java:614)
>         at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:140)
>         at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:135)
>         at org.apache.cassandra.db.compaction.CompactionTask.execute(CompactionTask.java:179)
>         at org.apache.cassandra.db.compaction.LeveledCompactionTask.execute(LeveledCompactionTask.java:47)
>         at org.apache.cassandra.db.compaction.CompactionManager$1.call(CompactionManager.java:131)
>         at org.apache.cassandra.db.compaction.CompactionManager$1.call(CompactionManager.java:114)
>         at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
>         at java.util.concurrent.FutureTask.run(FutureTask.java:138)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
> This was Sylvain's analysis:
> I don't have much better news. Basically it seems the 2 last MB of the file are complete garbage (which also explain the mmap error btw). And given where the corruption actually starts, it suggests that it's either a very low level bug in our file writer code that start writting bad data at some point for some reason, or it's corruption not related to Cassandra. But given that, a Cassandra bug sounds fairly unlikely.
> You said that you saw that corruption more than once. Could you be more precise? In particular, did you get it on different hosts? Also, what file system are you using?
> If you do happen to have another instance of a corrupted sstable (ideally from some other host) that you can share, please don't hesitate. I could try to look if I find something common between the two.

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