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From Gaojinchao <gaojinc...@huawei.com>
Subject Re: A requirement to change time of the Hbase cluster.
Date Wed, 26 Oct 2011 02:36:11 GMT
Thanks for your reply.
Our application scenario, The equipment and network is not our, Operators may do some of the
equipment and network adjustment.
In this case, These are some of the uncertainties. 
So we hope to add a choice about metadata is not time-dependent. Just like use data can use
a number as a timestamp .
If we can do this, the effect for time will be smaller. We don't use the ntp server, the cluster
also can work normal ?
Can I open a file? I will try to make a patch and share my mind.

-----邮件原件-----
发件人: Michel Segel [mailto:michael_segel@hotmail.com] 
发送时间: 2011年10月26日 3:55
收件人: user@hbase.apache.org
抄送: user@hbase.apache.org
主题: Re: A requirement to change time of the Hbase cluster.

Maybe I'm missing something...

The purpose of using an ntp server is that your machines all have the same time. Also you
would sync your ntp server clock to one of the global ntp servers so that you have an accurate
clock for your network...

You shouldn't have to restart your cluster unless your clocks are all way off...

Sent from a remote device. Please excuse any typos...

Mike Segel

On Oct 25, 2011, at 5:14 AM, Gaojinchao <gaojinchao@huawei.com> wrote:

> Perhaps we should. add a choice of supporting incremental meta-data. All the timestamp
is incremental, These data do not rely on the system time.
> 
> -----邮件原件-----
> 发件人: Gaojinchao [mailto:gaojinchao@huawei.com] 
> 发送时间: 2011年10月25日 12:33
> 收件人: user@hbase.apache.org
> 主题: A requirement to change time of the Hbase cluster.
> 
> Hi all,
> We have a requirement to change time of the Hbase cluster.
> The scene is the cluster changes the ntp server(my customer may do this),
> We are ready to do this:
> 1. stop the cluster
> 2. change the ntp server
> 3. start the cluster.
> But the cluster may move to one ntp server which system is slower.
> we find the meta data can't update becuase newly added record is covered by old record
and the cluster don't run normal.
> I have a way to deal with this situation. before we update the meta data ,we can get
it firstly and then compare the timestamp with the system time.
> if system time is lower than timestamp, updating metadata can use as timestamp +1.
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