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RE: Lots of Different Kind of Datanode Errors
   - Andy
From: Gokulakannan M <[EMAIL PROTECTED]>
Subject: RE: Lots of Different Kind of Datanode Errors
Date: Monday, June 7, 2010, 10:31 PM


Hi Andy,


            What is the reference of that fix?






From: Andrew Purtell

Sent: Tuesday, June 08, 2010 1:24


Subject: Re: Lots of Different
Kind of Datanode Errors

  Current synchronization on FSDataset seems not
  quite right. Doing what amounted to applying Todd's patch that modifies
  FSDataSet to use reentrant rwlocks cleared up that type of problem for
    - Andy

  From: Jeff Whiting <[EMAIL PROTECTED]>

  Subject: Re: Lots of Different Kind of Datanode Errors


  Date: Monday, June 7, 2010, 10:02 AM
  Thanks for the replies.  I have turned off swap
  on all the machines to prevent any swap problems.  I was pounding my
  hard drives quite hard.  I had a simulated 60 clients loading data as
  fast as I could into hbase with a map reduce export job going at the same
  time.  Would that scenario explain some of the errors I was seeing?


  Over the weekend under more of a normal load I haven't not any exception
  except for about 6 of these:

  2010-06-05 03:46:41,229 ERROR datanode.DataNode (DataXceiver.java:run(131)) -
  storageID=DS-1806250311-, infoPort=50075,

  org.apache.hadoop.hdfs.server.datanode.BlockAlreadyExistsException: Block
  blk_-1677111232590888964_4471547 is valid, and cannot be written to.



  The reason the config shows 4096 is because I increased the xceiver account
  after the first email message in this thread.




  Allen Wittenauer wrote:  
  On Jun 4, 2010, at 12:03 PM, Todd Lipcon wrote:     
  Hi Jeff,  That seems like a reasonable config, but the error message you pasted indicated xceivers was set to 2048 instead of 4096.  Also, in my experience SocketTimeoutExceptions are usually due to swapping. Verify that your machines aren't swapping when you're under load.     
  Or doing any other heavy disk IO.     
  -- Jeff WhitingQualtrics Senior Software [EMAIL PROTECTED]