hadoop-common-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Linden Hillenbrand <lin...@cloudera.com>
Subject Re: DataBlockScanner
Date Wed, 28 Sep 2011 04:19:08 GMT
Bourne,

There is only one datanode? "The "Verification succeeded" messages are from
a Datanode background housekeeping task, DataBlockScanner, which attempts to
discover any replicas that have become corrupt. If it finds one (which
should be rare), it tells the Namenode the replica has become corrupted, and
the NN will re-replicate it from a good copy on another DN.

DataBlockScanner may consume up to 100% of one CPU core on the DN, but no
more. It is very unlikely to have caused the DN to become unable to do its
high-priority work, like sending heartbeats and responding to Clients.
Unless you're running DN on single-core boxes, look to network problems or
Namenode overload as more likely explanations for the problem."

Also, if this is the case there are most likely a multitude of issues,
including the fact that you most likely have your replication factor set to
3 "dfs.replication" in your hdfs-site.xml.

Best,
Linden

2011/9/27 bourne1900 <bourne1900@yahoo.cn>

> Hi all,
> I have a client which puts files into HDFS ceaselessly, and there is only a
> datanode. When client puts about one million files, the datanode looks like
> down, and its log shows datanode is scaning:
> ---------------------------------------
> 2011-09-27 21:06:08,847 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_-8817786728284511104_1607418
> 2011-09-27 21:06:08,847 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_7628005260214492530_685287
> 2011-09-27 21:06:08,857 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_3044966277902621448_209467
> 2011-09-27 21:06:08,857 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_-505304627472587445_835974
> 2011-09-27 21:06:08,857 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_-226719360211181325_1144975
> 2011-09-27 21:06:12,388 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_3213691118040927179_170657
> 2011-09-27 21:06:12,389 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_-9019347929564406646_1012577
> 2011-09-27 21:06:12,389 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_-2347051438046583110_1609425
> 2011-09-27 21:06:12,389 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_-4660304336058637273_1057518
> 2011-09-27 21:06:12,390 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_4096281764881365361_1382370
> 2011-09-27 21:06:12,390 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_8264744903011499929_759123
> 2011-09-27 21:06:12,390 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_-8834278583248350231_719366
> 2011-09-27 21:06:12,390 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_359275864493028886_658067
> 2011-09-27 21:06:12,400 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_8571527510224016416_105224
> 2011-09-27 21:06:12,400 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_186525628134016242_700602
> 2011-09-27 21:06:12,400 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_-8143225753098515849_822080
> 2011-09-27 21:06:12,401 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_-2930103651790870445_855083
> 2011-09-27 21:06:12,408 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_4875601391443064624_402747
> 2011-09-27 21:06:12,409 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_7845835324800093130_821735
> 2011-09-27 21:06:12,416 INFO
> org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification
> succeeded for blk_-8470066700863973556_553973
>
>
> I am not sure if the scan makes datanode looks like down?
>
> Thanks.
> Best regards
> Bourne




-- 
Linden Hillenbrand
Customer Operations Engineer

Phone:  650.644.3900 x4946
Email:   linden@cloudera.com
Twitter: @lhillenbrand
Data:    http://www.cloudera.com

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message