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From Mark Kerzner <mark.kerz...@shmsoft.com>
Subject Re: Replacing a hard drive on a slave
Date Wed, 28 Nov 2012 15:43:18 GMT
Somebody asked me, and I did not know what to answer. I will ask them your
questions.

Thank you.
Mark

On Wed, Nov 28, 2012 at 7:41 AM, Michael Segel <michael_segel@hotmail.com>wrote:

> Silly question, why are you worrying about this?
>
> In a production the odds of getting a replacement disk in service within
> 10 minutes after a fault is detected is highly improbable.
>
> Why do you care that the blocks are replicated to another node?
> After you replace the disk, bounce the node (restart DN) (RS if running) ,
> you can always force a rebalance of the cluster.
>
>
> On Nov 28, 2012, at 9:22 AM, Mark Kerzner <mark.kerzner@shmsoft.com>
> wrote:
>
> What happens if I stop the datanode, miss the 10 min 30 seconds deadline,
> and restart the datanode say 30 minutes later? Will Hadoop re-use the data
> on this datanode, balancing it with HDFS? What happens to those blocks that
> correspond to file that have been updated meanwhile?
>
> Mark
>
> On Wed, Nov 28, 2012 at 6:51 AM, Stephen Fritz <stephenf@cloudera.com>wrote:
>
>> HDFS will not start re-replicating blocks from a dead DN for 10 minutes
>> 30 seconds by default.
>>
>> Right now there isn't a good way to replace a disk out from under a
>> running datanode, so the best way is:
>> - Stop the DN
>> - Replace the disk
>> - Restart the DN
>>
>>
>>
>>
>> On Wed, Nov 28, 2012 at 9:14 AM, Mark Kerzner <mark.kerzner@shmsoft.com>wrote:
>>
>>> Hi,
>>>
>>> can I remove one hard drive from a slave but tell Hadoop not to
>>> replicate missing blocks for a few minutes, because I will return it back?
>>> Or will this not work at all, and will Hadoop continue replicating, since I
>>> removed blocks, even for a short time?
>>>
>>> Thank you. Sincerely,
>>> Mark
>>>
>>
>>
>
>

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