Hadoop version: hadoop-0.20.205.0

My NN machine has 2 IP addresses and 2 hostnames assigned to them
respectively. I have configured "fs.default.name" using one of the
hostnames and used the cluster for a while.

Now, I may have to move the "fs.default.name" to the other IP/hostname of
the same machine. If no other configurations change (such as the
directories), can I simply change "fs.default.name" to the new hostname,
restart the NN and expect the same filesystem is intact?

Thanks,
James

Hi Jianhui,

If you only has hadoop and not HBase, maybe there is no problem.
Last time we changed IP addresses but not hostname. Our hadoop version is
hadoop 1.0.2, HBase is 0.92.  At beginning, it's ok. But after about 2
hours, the second name node exited and couldn't start , reported
NullPointException. Then we restarted all nodes, but NN couldn't start and
reported the same error.

So you can just have a test. Before your test, REMEMBER to BACKUP ALL YOUR
DATA, especially the name node data and HBase -META-,-ROOT- table.

Good Luck!
Andy Zhou

2013/1/6 Jianhui Zhang <[EMAIL PROTECTED]>

> Hadoop version: hadoop-0.20.205.0
>
> My NN machine has 2 IP addresses and 2 hostnames assigned to them
> respectively. I have configured "fs.default.name" using one of the
> hostnames and used the cluster for a while.
>
> Now, I may have to move the "fs.default.name" to the other IP/hostname of
> the same machine. If no other configurations change (such as the
> directories), can I simply change "fs.default.name" to the new hostname,
> restart the NN and expect the same filesystem is intact?
>
> Thanks,
> James
>

Hi James,
This should be fine, but just wanted to add that you will need to also make
the change on your other nodes within the cluster, so they know how to
contact the filesystem.

Regards,
Robert

On Sun, Jan 6, 2013 at 12:18 AM, Jagat Singh <[EMAIL PROTECTED]> wrote:

> Yes your data is safe.
>
>
>
>
> On Sun, Jan 6, 2013 at 6:41 PM, Jianhui Zhang <[EMAIL PROTECTED]>wrote:
>
>> Hadoop version: hadoop-0.20.205.0
>>
>> My NN machine has 2 IP addresses and 2 hostnames assigned to them
>> respectively. I have configured "fs.default.name" using one of the
>> hostnames and used the cluster for a while.
>>
>> Now, I may have to move the "fs.default.name" to the other IP/hostname
>> of the same machine. If no other configurations change (such as the
>> directories), can I simply change "fs.default.name" to the new hostname,
>> restart the NN and expect the same filesystem is intact?
>>
>> Thanks,
>> James
>>
>
>

Thank everybody for the responses.

James

On Mon, Jan 7, 2013 at 12:49 PM, Robert Molina <[EMAIL PROTECTED]>wrote:

> Hi James,
> This should be fine, but just wanted to add that you will need to also
> make the change on your other nodes within the cluster, so they know how to
> contact the filesystem.
>
> Regards,
> Robert
>
>
> On Sun, Jan 6, 2013 at 12:18 AM, Jagat Singh <[EMAIL PROTECTED]> wrote:
>
>> Yes your data is safe.
>>
>>
>>
>>
>> On Sun, Jan 6, 2013 at 6:41 PM, Jianhui Zhang <[EMAIL PROTECTED]>wrote:
>>
>>> Hadoop version: hadoop-0.20.205.0
>>>
>>> My NN machine has 2 IP addresses and 2 hostnames assigned to them
>>> respectively. I have configured "fs.default.name" using one of the
>>> hostnames and used the cluster for a while.
>>>
>>> Now, I may have to move the "fs.default.name" to the other IP/hostname
>>> of the same machine. If no other configurations change (such as the
>>> directories), can I simply change "fs.default.name" to the new
>>> hostname, restart the NN and expect the same filesystem is intact?
>>>
>>> Thanks,
>>> James
>>>
>>
>>
>