Jean-Marc Spaggiari 2012-11-22, 16:27
Jean-Marc Spaggiari 2012-11-22, 16:48
Harsh J 2012-11-22, 17:25
Jean-Marc Spaggiari 2012-11-22, 17:33
Please follow the tips provided at
In short, if you use a non-HA NameNode setup:
- Yes the NN is a very vital persistence point in running HDFS and its
data should be redundantly stored for safety.
- You should, in production, configure your NameNode's image and edits
disk (dfs.name.dir in 1.x+, or dfs.namenode.name.dir in 0.23+/2.x+) to
be a dedicated one with adequate free space for gradual growth, and
should configure multiple disks (with one off-machine NFS point highly
recommended for easy recovery) for adequate redundancy.
If you instead use a HA NameNode setup (I'd highly recommend doing
this since it is now available), the presence of > 1 NameNodes and the
journal log mount or quorum setup would automatically act as
safeguards for the FS metadata.
On Thu, Nov 22, 2012 at 11:03 PM, Jean-Marc Spaggiari
<[EMAIL PROTECTED]> wrote:
> Hi Harsh,
> Thanks for pointing me to this link. I will take a close look at it.
> So with 1.x and 0.23.x, what's the impact on the data if the namenode
> server hard-drive die? Is there any critical data stored locally? Or I
> simply need to build a new namenode, start it and restart all my
> namenodes to find my data back?
> I can deal with my application not beeing available, but loosing data
> can be a bigger issue.
> 2012/11/22, Harsh J <[EMAIL PROTECTED]>:
>> Hey Jean,
>> The 1.x, 0.23.x release lines both don't have NameNode HA features.
>> The current 2.x releases carry HA-NN abilities, and this is documented
>> On Thu, Nov 22, 2012 at 10:18 PM, Jean-Marc Spaggiari
>> <[EMAIL PROTECTED]> wrote:
>>> Replying to myself ;)
>>> By digging a bit more I figured that 1.0 version is older than 0.23.4
>>> version and that backupnodes are on 0.23.4. Secondarynamenodes on 1.0
>>> are now deprecated.
>>> I'm still a bit mixed up on the way to achieve HA for the namenode
>>> (1.0 or 0.23.4) but I will continue to dig over internet.
>>> 2012/11/22, Jean-Marc Spaggiari <[EMAIL PROTECTED]>:
>>>> I'm reading a bit about hadoop and I'm trying to increase the HA of my
>>>> current cluster.
>>>> Today I have 8 datanodes and one namenode.
>>>> By reading here: http://www.aosabook.org/en/hdfs.html I can see that a
>>>> Checkpoint node might be a good idea.
>>>> So I'm trying to start a checkpoint node. I looked at the hadoop
>>>> online doc. There is a link toe describe the command usage "For
>>>> command usage, see namenode." but this link is not working. Also, if I
>>>> try hadoop-deamon.sh start namenode -checkpoint as discribed in the
>>>> documentation, it's not starting.
>>>> So I'n wondering, is there anywhere where I can find up to date
>>>> documentation about the checkpoint node? I will most probably try the
>>>> I'm using hadoop 1.0.3. The options I have to start on this version
>>>> are namenode, secondarynamenode, datanode, dfsadmin, mradmin, fsck and
>>>> fs. Should I start some secondarynamenodes instead of backupnode and
>> Harsh J
Jean-Marc Spaggiari 2012-11-22, 18:29
Harsh J 2012-11-22, 18:42
Jean-Marc Spaggiari 2012-11-22, 19:09
Jean-Marc Spaggiari 2012-12-01, 02:11
Jean-Marc Spaggiari 2012-12-01, 02:25
Harsh J 2012-12-01, 04:24
ac@...) 2012-12-01, 04:11