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From Jamie Cockrill <jamie.cockr...@gmail.com>
Subject Re: HBase on same boxes as HDFS Data nodes
Date Wed, 07 Jul 2010 17:30:24 GMT
Bad news, it looks like my xcievers is set as it should be, it's in
the hdfs-site.xml and looking at the job.xml of one of my jobs in the
job-tracker, it's showing that property as set to 2047. I've cat |
grepped one of the datanode logs and although there were a few in
there, they were from a few months ago. I've upped my MAX_FILESIZE on
my table to 1GB to see if that helps (not sure if it will!).

Thanks,

Jamie

On 7 July 2010 18:12, Jean-Daniel Cryans <jdcryans@apache.org> wrote:
> xcievers exceptions will be in the datanodes' logs, and your problem
> totally looks like it. 0.20.5 will have the same issue (since it's on
> the HDFS side)
>
> J-D
>
> On Wed, Jul 7, 2010 at 10:08 AM, Jamie Cockrill
> <jamie.cockrill@gmail.com> wrote:
>> Hi Todd & JD,
>>
>> Environment:
>> All (hadoop and HBase) installed as of karmic-cdh3, which means:
>> Hadoop 0.20.2+228
>> HBase 0.89.20100621+17
>> Zookeeper 3.3.1+7
>>
>> Unfortunately my whole cluster of regionservers have now crashed, so I
>> can't really say if it was swapping too much. There is a DEBUG
>> statement just before it crashes saying:
>>
>> org.apache.hadoop.hbase.regionserver.wal.HLog: closing hlog writer in
>> hdfs://<somewhere on my HDFS, in /hbase>
>>
>> What follows is:
>>
>> WARN org.apache.hadoop.hdfs.DFSClient: DataStreamer Exception:
>> org.apache.hadoop.ipc.RemoteException:
>> org.apache.hadoop.hdfs.server.namenode.LeaseExpiredException: No lease
>> on <file location as above> File does not exist. Holder
>> DFSClient_-11113603 does not have any open files
>>
>> It then seems to try and do some error recovery (Error Recovery for
>> block null bad datanode[0] nodes == null), fails (Could not get block
>> locations. Source file "<hbase file as before>" - Aborting). There is
>> then an ERROR org.apache...HRegionServer: Close and delete failed.
>> There is then a similar LeaseExpiredException as above.
>>
>> There are then a couple of messages from HRegionServer saying that
>> it's notifying master of its shutdown and stopping itself. The
>> shutdown hook then fires and the RemoteException and
>> LeaseExpiredExceptions are printed again.
>>
>> ulimit is set to 65000 (it's in the regionserver log, printed as I
>> restarted the regionserver), however I haven't got the xceivers set
>> anywhere. I'll give that a go. It does seem very odd as I did have a
>> few of them fall over one at a time with a few early loads, but that
>> seemed to be because the regions weren't splitting properly, so all
>> the traffic was going to one node and it was being overwhelmed. Once I
>> throttled it, after one load it a region split seemed to get
>> triggered, which flung regions all over, which made subsequent loads
>> much more distributed. However, perhaps the time-bomb was ticking...
>> I'll  have a go at specifying the xcievers property. I'm pretty
>> certain i've got everything else covered, except the patches as
>> referenced in the JIRA.
>>
>> I just grepped some of the log files and didn't get an explicit
>> exception with 'xciever' in it.
>>
>> I am considering downgrading(?) to 0.20.5, however because everything
>> is installed as per karmic-cdh3, I'm a bit reluctant to do so as
>> presumably Cloudera has tested each of these versions against each
>> other? And I don't really want to introduce further versioning issues.
>>
>> Thanks,
>>
>> Jamie
>>
>>
>> On 7 July 2010 17:30, Jean-Daniel Cryans <jdcryans@apache.org> wrote:
>>> Jamie,
>>>
>>> Does your configuration meets the requirements?
>>> http://hbase.apache.org/docs/r0.20.5/api/overview-summary.html#requirements
>>>
>>> ulimit and xcievers, if not set, are usually time bombs that blow off when
>>> the cluster is under load.
>>>
>>> J-D
>>>
>>> On Wed, Jul 7, 2010 at 9:11 AM, Jamie Cockrill <jamie.cockrill@gmail.com>wrote:
>>>
>>>> Dear all,
>>>>
>>>> My current HBase/Hadoop architecture has HBase region servers on the
>>>> same physical boxes as the HDFS data-nodes. I'm getting an awful lot
>>>> of region server crashes. The last thing that happens appears to be a
>>>> DroppedSnapshot Exception, caused by an IOException: could not
>>>> complete write to file <file on HDFS>. I am running it under load,
how
>>>> heavy that is I'm not sure how that is quantified, but I'm guessing it
>>>> is a load issue.
>>>>
>>>> Is it common practice to put region servers on data-nodes? Is it
>>>> common to see region server crashes when either the HDFS or region
>>>> server (or both) is under heavy load? I'm guessing that is the case as
>>>> I've seen a few similar posts. I've not got a great deal of capacity
>>>> to be separating region servers from HDFS data nodes, but it might be
>>>> an argument I could make.
>>>>
>>>> Thanks
>>>>
>>>> Jamie
>>>>
>>>
>>
>

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