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HDFS >> mail # user >> disk used percentage is not symmetric on datanodes (balancer)


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Re: disk used percentage is not symmetric on datanodes (balancer)
Any more follow ups ?

Thanks
-Tapas

On Mar 19, 2013, at 9:55 AM, Tapas Sarangi <[EMAIL PROTECTED]> wrote:

>
> On Mar 18, 2013, at 11:50 PM, Harsh J <[EMAIL PROTECTED]> wrote:
>
>> What do you mean that the balancer is always active?
>
> meaning, the same process is active for a long time. The process that starts may not be exiting at all. We have a cron job set to run it every 10 minutes, but that's not in effect because the process may never exit.
>
>
>> It is to be used
>> as a tool and it exits once it balances in a specific run (loops until
>> it does, but always exits at end). The balancer does balance based on
>> usage percentage so that is what you're probably looking for/missing.
>>
>
> May be. How does the balancer look for the usage percentage ?
>
> -Tapas
>
>
>> On Tue, Mar 19, 2013 at 6:56 AM, Tapas Sarangi <[EMAIL PROTECTED]> wrote:
>>> Hi,
>>>
>>> On Mar 18, 2013, at 8:21 PM, 李洪忠 <[EMAIL PROTECTED]> wrote:
>>>
>>> Maybe you need to modify the rackware script to make the rack balance, ie,
>>> all the racks are the same size,  on rack by 6 small nodes, one rack by 1
>>> large nodes.
>>> P.S.
>>> you need to reboot the cluster for rackware script modify.
>>>
>>>
>>> Like I mentioned earlier in my reply to Bertrand, we haven't considered rack
>>> awareness for the cluster, currently it is considered as just one rack. Can
>>> that be the problem ? I don't know…
>>>
>>> -Tapas
>>>
>>>
>>>
>>> 于 2013/3/19 7:17, Bertrand Dechoux 写道:
>>>
>>> And by active, it means that it does actually stops by itself? Else it might
>>> mean that the throttling/limit might be an issue with regard to the data
>>> volume or velocity.
>>>
>>> What threshold is used?
>>>
>>> About the small and big datanodes, how are they distributed with regards to
>>> racks?
>>> About files, how is used the replication factor(s) and block size(s)?
>>>
>>> Surely trivial questions again.
>>>
>>> Bertrand
>>>
>>> On Mon, Mar 18, 2013 at 10:46 PM, Tapas Sarangi <[EMAIL PROTECTED]>
>>> wrote:
>>>>
>>>> Hi,
>>>>
>>>> Sorry about that, had it written, but thought it was obvious.
>>>> Yes, balancer is active and running on the namenode.
>>>>
>>>> -Tapas
>>>>
>>>> On Mar 18, 2013, at 4:43 PM, Bertrand Dechoux <[EMAIL PROTECTED]> wrote:
>>>>
>>>> Hi,
>>>>
>>>> It is not explicitly said but did you use the balancer?
>>>> http://hadoop.apache.org/docs/r1.0.4/commands_manual.html#balancer
>>>>
>>>> Regards
>>>>
>>>> Bertrand
>>>>
>>>> On Mon, Mar 18, 2013 at 10:01 PM, Tapas Sarangi <[EMAIL PROTECTED]>
>>>> wrote:
>>>>>
>>>>> Hello,
>>>>>
>>>>> I am using one of the old legacy version (0.20) of hadoop for our
>>>>> cluster. We have scheduled for an upgrade to the newer version within a
>>>>> couple of months, but I would like to understand a couple of things before
>>>>> moving towards the upgrade plan.
>>>>>
>>>>> We have about 200 datanodes and some of them have larger storage than
>>>>> others. The storage for the datanodes varies between 12 TB to 72 TB.
>>>>>
>>>>> We found that the disk-used percentage is not symmetric through all the
>>>>> datanodes. For larger storage nodes the percentage of disk-space used is
>>>>> much lower than that of other nodes with smaller storage space. In larger
>>>>> storage nodes the percentage of used disk space varies, but on average about
>>>>> 30-50%. For the smaller storage nodes this number is as high as 99.9%. Is
>>>>> this expected ? If so, then we are not using a lot of the disk space
>>>>> effectively. Is this solved in a future release ?
>>>>>
>>>>> If no, I would like to know  if there are any checks/debugs that one can
>>>>> do to find an improvement with the current version or upgrading hadoop
>>>>> should solve this problem.
>>>>>
>>>>> I am happy to provide additional information if needed.
>>>>>
>>>>> Thanks for any help.
>>>>>
>>>>> -Tapas
>>>>>
>>>>
>>>
>>>
>>>
>>> --
>>> Bertrand Dechoux
>>>
>>>
>>>
>>
>>
>>
>> --
>> Harsh J
>