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From Ramkrishna S Vasudevan <ramakrish...@huawei.com>
Subject RE: A question about Hmaster startup.
Date Tue, 19 Apr 2011 04:47:30 GMT
Hi 

Yes. In Hbase 0.90.2 this change has been done.

The HMaster tries creating the /hbase/hbase.version and when the DN comes up the NN throws
an exception saying AlreadyCreatedException.

so the HMaster is not able to start.

Regards
Ram

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-----Original Message-----
From: Gaojinchao [mailto:gaojinchao@huawei.com] 
Sent: Tuesday, April 19, 2011 9:57 AM
To: user@hbase.apache.org
Subject: Re: A question about Hmaster startup.

Sorry. 
My queston is:
If HMaster is started after NN without starting DN in Hbase 090.2 then HMaster is not able
to start due to AlreadyCreatedException for /hbase/hbase.version.
In hbase version 0.90.1, It will wait for data node start up.

I try to dig the code and find the code changes in hbase version 0.90.2 and can't find issue
for this.


-----邮件原件-----
发件人: jdcryans@gmail.com [mailto:jdcryans@gmail.com] 代表 Jean-Daniel Cryans
发送时间: 2011年4月19日 11:59
收件人: user@hbase.apache.org
主题: Re: A question about Hmaster startup.

Vague question, I'll try my best answer.

This was committed as part of "HBASE-1816 Master rewrite", and in the
comments I can read:

+ Move fs methods out of HMaster to FSUtils.

And if you you look at FSUtils, you'll see how it's done now.

J-D

On Mon, Apr 18, 2011 at 8:48 PM, Gaojinchao <gaojinchao@huawei.com> wrote:
> Why delete this code ?
>
> // Are there any data nodes up yet?
>    // Currently the safe mode check falls through if the namenode is up but no
>    // datanodes have reported in yet.
>    try {
>      while (dfs.getDataNodeStats().length == 0) {
>        LOG.info("Waiting for dfs to come up...");
>        try {
>          Thread.sleep(wait);
>        } catch (InterruptedException e) {
>          //continue
>        }
>      }
>    } catch (IOException e) {
>      // getDataNodeStats can fail if superuser privilege is required to run
>      // the datanode report, just ignore it
>    }
>


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