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HBase >> mail # user >> HBase scan performance decreases over time.

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Re: HBase scan performance decreases over time.
There is property dfs.balance.bandwidthPerSec in hdfs-site.xml
        Specifies the maximum amount of bandwidth that each datanode
        can utilize for the balancing purpose in term of
        the number of bytes per second.
Thank you!

Leonid Fedotov
On Nov 5, 2012, at 10:14 AM, Asaf Mesika wrote:

> Where is this settings located?
> Sent from my iPhone
> On 5 בנוב 2012, at 15:05, Michael Segel <[EMAIL PROTECTED]> wrote:
>> There's an HDFS bandwidth setting which is set to 10MB/s.
>> Way too low for even 1GBe.
>> Have you modified this setting yet?
>> -Mike
>> On Nov 3, 2012, at 2:50 PM, David Koch <[EMAIL PROTECTED]> wrote:
>>> Hello Ted,
>>> We never initiate major compaction manually. I have not looked at I/O
>>> balance between nodes in detail. We have noticed that after running for a
>>> couple of weeks HBase seems to spend hours pushing blocks between nodes in
>>> order to optimize things. We add data daily in one ~30gb push to several
>>> tables. Sometimes nodes get added to the running system.
>>> Where can I get more information on how to carry out performance related
>>> HBase administrative tasks?
>>> Thank you,
>>> /David
>>> On Sat, Nov 3, 2012 at 4:42 PM, Ted Yu <[EMAIL PROTECTED]> wrote:
>>>> Can you tell us how often you run major compaction after the import ?
>>>> Have you noticed imbalanced read / write requests in the cluster ? Meaning
>>>> subset of region servers receive bulk of the writes.
>>>> We do some manual movement of regions when the above happens.
>>>> Cheers
>>>> On Sat, Nov 3, 2012 at 8:12 AM, David Koch <[EMAIL PROTECTED]> wrote:
>>>>> Hello,
>>>>> Every now and then we need to flatten our cluster and re-import all data
>>>>> from log files (changes in data format, etc.) Afterwards we notice a
>>>>> significant increase in scan performance. As data is added and shuffled
>>>>> around between region servers, performance goes down again over time
>>>> (say a
>>>>> couple of weeks). Are there any routine operations that one should run
>>>>> manually, or settings to activate in the HBase configuration to keep the
>>>>> data well distributed? We use HBase 0.92 as part of a Cloudera4 cluster.
>>>>> Thank you,
>>>>> /David