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https://issues.apache.org/jira/browse/HDFS-1594?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13020373#comment-13020373
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Eli Collins commented on HDFS-1594:
-----------------------------------
bq. 1. The original JIRA description indicated that this problem was caused
only by the disk filling up, yet the original patches also monitor for a
near-full JVM heap. I left the memory checking in this reworked patch, but I
think this feature should probably be removed. Unclear how this would interact
with Java GC, and unclear if entering safemode would actually help the
situation.
I agree, should be pulled out to a separate jira.
bq. 3. Todd mentioned that he's seen edit log corruptions from the log volume
filling up. Perhaps we should add an additional configuration option to let the
user specify arbitrary volumes to check, besides just the volumes containing
the edits/name dirs?
Good idea, there's nothing edits specific here. Would need to add a test that
if the admin does pass in the volume that hosts the edits log it doesn't
conflict with the default behavior (eg double monitoring).
bq. 3. I switched the configuration of disk space amount from a percentage to a
number of bytes remaining, since volume sizes may differ, and thus a fixed
amount of space reserved seems more appropriate. Perhaps there should be a way
to specify the threshold per-volume?
What's the intended behavior if there are n disks and one fills up before the
others? Seems like this volume should be taken off-line and the NN does not
enter SM. If there's just a global threshold would this cause the overall
threshold to drop (because the removed volume's free space not longer counts
towards the total), causing a cascade where the other volumes go off-line? This
would suggest a threshold per volume. Though if we can make a single, simple
threshold work that seems better from a usability perspective.
bq. 4. I'm a little concerned that we might see a problem where the NN will
reach the threshold and then thrash in and out of safemode as it sits on the
cusp of the configured free space. Perhaps we should not automatically leave
safemode in the event the resources later return to normal? Or make this
behavior configurable? It seems to me that an NN volume running out of space
should be a cause for concern, so it might be reasonable for an admin to have
to manually force the NN out of safe mode.
Seems there are two scenarios here:
a. The admin can easily free up some space
b. The admin can not easily free up space (eg needs to compact the log because
the 2NN wasn't running for a while, need to resize the volume, replace the disk
etc).
In both cases I think the admin would want to have to manually tell the NN to
leave SM while they are working (eg w/o them explicitly telling it to do so).
If they want automatic behavior they can continuosly monitor/roll on these
volumes so they don't get into this scenario, and they don't want the
monitoring/rolling to race with the free space detection (eg they'd want to
have to take action if this process ever crosses the threshold they set). Ie
seems like once you've gone into SM due to lack of free space you should stay
there until the admin has had a chance to rectify.
> When the disk becomes full Namenode is getting shutdown and not able to
> recover
> -------------------------------------------------------------------------------
>
> Key: HDFS-1594
> URL: https://issues.apache.org/jira/browse/HDFS-1594
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: name-node
> Affects Versions: 0.21.0, 0.21.1, 0.22.0
> Environment: Linux linux124 2.6.27.19-5-default #1 SMP 2009-02-28
> 04:40:21 +0100 x86_64 x86_64 x86_64 GNU/Linux
> Reporter: Devaraj K
> Assignee: Aaron T. Myers
> Fix For: 0.23.0
>
> Attachments: HDFS-1594.patch, HDFS-1594.patch, HDFS-1594.patch,
> hadoop-root-namenode-linux124.log, hdfs-1594.0.patch, hdfs-1594.1.patch,
> hdfs-1594.2.patch
>
>
> When the disk becomes full name node is shutting down and if we try to start
> after making the space available It is not starting and throwing the below
> exception.
> {code:xml}
> 2011-01-24 23:23:33,727 ERROR
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem: FSNamesystem
> initialization failed.
> java.io.EOFException
> at java.io.DataInputStream.readFully(DataInputStream.java:180)
> at org.apache.hadoop.io.UTF8.readFields(UTF8.java:117)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImageSerialization.readString(FSImageSerialization.java:201)
> at
> org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadEditRecords(FSEditLogLoader.java:185)
> at
> org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadFSEdits(FSEditLogLoader.java:93)
> at
> org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadFSEdits(FSEditLogLoader.java:60)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSEdits(FSImage.java:1089)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSImage(FSImage.java:1041)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:487)
> at
> org.apache.hadoop.hdfs.server.namenode.FSDirectory.loadFSImage(FSDirectory.java:149)
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.initialize(FSNamesystem.java:306)
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.<init>(FSNamesystem.java:284)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.loadNamesystem(NameNode.java:328)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:356)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:577)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:570)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1529)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1538)
> 2011-01-24 23:23:33,729 ERROR
> org.apache.hadoop.hdfs.server.namenode.NameNode: java.io.EOFException
> at java.io.DataInputStream.readFully(DataInputStream.java:180)
> at org.apache.hadoop.io.UTF8.readFields(UTF8.java:117)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImageSerialization.readString(FSImageSerialization.java:201)
> at
> org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadEditRecords(FSEditLogLoader.java:185)
> at
> org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadFSEdits(FSEditLogLoader.java:93)
> at
> org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadFSEdits(FSEditLogLoader.java:60)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSEdits(FSImage.java:1089)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSImage(FSImage.java:1041)
> at
> org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:487)
> at
> org.apache.hadoop.hdfs.server.namenode.FSDirectory.loadFSImage(FSDirectory.java:149)
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.initialize(FSNamesystem.java:306)
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.<init>(FSNamesystem.java:284)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.loadNamesystem(NameNode.java:328)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:356)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:577)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:570)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1529)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1538)
> 2011-01-24 23:23:33,730 INFO org.apache.hadoop.hdfs.server.namenode.NameNode:
> SHUTDOWN_MSG:
> /************************************************************
> SHUTDOWN_MSG: Shutting down NameNode at linux124/10.18.52.124
> ************************************************************/
> {code}
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