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List:       hadoop-user
Subject:    Re: best command line way to check up/down status of HDFS?
From:       Konstantin Shvachko <shv () yahoo-inc ! com>
Date:       2008-06-27 19:16:38
Message-ID: 48653C96.6050008 () yahoo-inc ! com
[Download RAW message or body]

True about the secondary, see also
http://wiki.apache.org/hadoop/FAQ#7

lohit wrote:
> If NameNode is down, secondary namenode does not serve requests. It is used to update the fsimage. 
> (http://hadoop.apache.org/core/docs/r0.17.0/hdfs_user_guide.html#Secondary+Namenode)
> 
> Thanks,
> Lohit
> 
> ----- Original Message ----
> From: Miles Osborne <miles@inf.ed.ac.uk>
> To: core-user@hadoop.apache.org
> Sent: Friday, June 27, 2008 10:30:14 AM
> Subject: Re: best command line way to check up/down status of HDFS?
> 
> in that case, do:
> 
> jps
> 
> and look for both the namenode and also the secondary node
> 
> Miles
> 
> 2008/6/27 Meng Mao <mengmao@gmail.com>:
> 
>> I was thinking of checking for both independently, and taking a logical OR.
>> Would that be sufficient?
>>
>> I'm trying to avoid file reading if possible. Not that reading through a
>> log
>> is that intensive,
>> but it'd be cleaner if I could poll either Hadoop itself or inspect the
>> processes running.
>>
>> On Fri, Jun 27, 2008 at 1:23 PM, Miles Osborne <miles@inf.ed.ac.uk> wrote:
>>
>>> that won't work since the namenode may be down, but the secondary
>> namenode
>>> may be up instead
>>>
>>> why not instead just look at the respective logs?
>>>
>>> Miles
>>>
>>> 2008/6/27 Meng Mao <mengmao@gmail.com>:
>>>
>>>> Is running:
>>>> ps aux | grep [\\.]NameNode
>>>>
>>>> and looking for a non empty response a good way to test HDFS up status?
>>>>
>>>> I'm assuming that if the NameNode process is down, then DFS is
>> definitely
>>>> down?
>>>> Worried that there'd be frequent cases of DFS being messed up but the
>>>> process still running just fine.
>>>>
>>>> On Fri, Jun 27, 2008 at 10:48 AM, Meng Mao <mengmao@gmail.com> wrote:
>>>>
>>>>> For a Nagios script I'm writing, I'd like a command-line method that
>>>> checks
>>>>> if HDFS is up and running.
>>>>> Is there a better way than to attempt a hadoop dfs command and check
>>> the
>>>>> error code?
>>>>>
>>>>
>>>>
>>>> --
>>>> hustlin, hustlin, everyday I'm hustlin
>>>>
>>>
>>>
>>> --
>>> The University of Edinburgh is a charitable body, registered in Scotland,
>>> with registration number SC005336.
>>>
>>
>>
>> --
>> hustlin, hustlin, everyday I'm hustlin
>>
> 
> 
> 
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