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From Adrien Mogenet <adrien.moge...@contentsquare.com>
Subject Re: High iowait in idle hbase cluster
Date Thu, 03 Sep 2015 16:57:32 GMT
Is the uptime of RS "normal"? No quick and global reboot that could lead
into a regiongi-reallocation-storm?

On 3 September 2015 at 18:42, Akmal Abbasov <akmal.abbasov@icloud.com>
wrote:

> Hi Adrien,
> I’ve tried to run hdfs fsck and hbase hbck, and hdfs is healthy, also
> hbase is consistent.
> I’m using default value of the replication, so it is 3.
> There are some under replicated
> HBase master(node 10.10.8.55) is reading constantly from regionservers.
> Only today, it send >150.000 HDFS_READ requests to each regionserver so
> far, while the hbase cluster is almost idle.
> What could cause this kind of behaviour?
>
> p.s. each node in the cluster have 2 core, 4 gb ram, just in case.
>
> Thanks.
>
>
> On 03 Sep 2015, at 17:46, Adrien Mogenet <adrien.mogenet@contentsquare.com>
> wrote:
>
> Is your HDFS healthy (fsck /)?
>
> Same for hbase hbck?
>
> What's your replication level?
>
> Can you see constant network use as well?
>
> Anything than might be triggered by the hbasemaster? (something like a
> virtually dead RS, due to ZK race-condition, etc.)
>
> Your 3-weeks-ago balancer shouldn't have any effect if you've ran a major
> compaction, successfully, yesterday.
>
> On 3 September 2015 at 16:32, Akmal Abbasov <akmal.abbasov@icloud.com>
> wrote:
>
>> I’ve started HDFS balancer, but then stopped it immediately after knowing
>> that it is not a good idea.
>> but it was around 3 weeks ago, is it possible that it had an influence on
>> the cluster behaviour I’m having now?
>> Thanks.
>>
>> On 03 Sep 2015, at 14:23, Akmal Abbasov <akmal.abbasov@icloud.com> wrote:
>>
>> Hi Ted,
>> No there is no short-circuit read configured.
>> The logs of datanode of the 10.10.8.55 are full of following messages
>> 2015-09-03 12:03:56,324 INFO
>> org.apache.hadoop.hdfs.server.datanode.DataNode.clienttrace: src: /
>> 10.10.8.55:50010, dest: /10.10.8.53:58622, bytes: 77, op: HDFS_READ,
>> cliID: DFSClient_NONMAPREDUCE_-483065515_1, offset: 0, srvID:
>> ee7d0634-89a3-4ada-a8ad-7848214397be, blockid:
>> BP-439084760-10.32.0.180-1387281790961:blk_1075349331_1612273, duration:
>> 276448307
>> 2015-09-03 12:03:56,494 INFO
>> org.apache.hadoop.hdfs.server.datanode.DataNode.clienttrace: src: /
>> 10.10.8.55:50010, dest: /10.10.8.53:58622, bytes: 538, op: HDFS_READ,
>> cliID: DFSClient_NONMAPREDUCE_-483065515_1, offset: 0, srvID:
>> ee7d0634-89a3-4ada-a8ad-7848214397be, blockid:
>> BP-439084760-10.32.0.180-1387281790961:blk_1075349334_1612276, duration:
>> 60550244
>> 2015-09-03 12:03:59,561 INFO
>> org.apache.hadoop.hdfs.server.datanode.DataNode.clienttrace: src: /
>> 10.10.8.55:50010, dest: /10.10.8.53:58622, bytes: 455, op: HDFS_READ,
>> cliID: DFSClient_NONMAPREDUCE_-483065515_1, offset: 0, srvID:
>> ee7d0634-89a3-4ada-a8ad-7848214397be, blockid:
>> BP-439084760-10.32.0.180-1387281790961:blk_1075351814_1614757, duration:
>> 755613819
>> There are >100.000 of them just for today. The situation with other
>> regionservers are similar.
>> Node 10.10.8.53 is hbase-master node, and the process on the port is also
>> hbase-master.
>> So if there is no load on the cluster, why there are so much IO happening?
>> Any thoughts.
>> Thanks.
>>
>> On 02 Sep 2015, at 21:57, Ted Yu <yuzhihong@gmail.com> wrote:
>>
>> I assume you have enabled short-circuit read.
>>
>> Can you capture region server stack trace(s) and pastebin them ?
>>
>> Thanks
>>
>> On Wed, Sep 2, 2015 at 12:11 PM, Akmal Abbasov <akmal.abbasov@icloud.com>
>> wrote:
>>
>>> Hi Ted,
>>> I’ve checked the time when addresses were changed, and this strange
>>> behaviour started weeks before it.
>>>
>>> yes, 10.10.8.55 is region server and 10.10.8.54 is a hbase master.
>>> any thoughts?
>>>
>>> Thanks
>>>
>>> On 02 Sep 2015, at 18:45, Ted Yu <yuzhihong@gmail.com> wrote:
>>>
>>> bq. change the ip addresses of the cluster nodes
>>>
>>> Did this happen recently ? If high iowait was observed after the change
>>> (you can look at ganglia graph), there is a chance that the change was
>>> related.
>>>
>>> BTW I assume 10.10.8.55 <http://10.10.8.55:50010/> is where your region
>>> server resides.
>>>
>>> Cheers
>>>
>>> On Wed, Sep 2, 2015 at 9:39 AM, Akmal Abbasov <akmal.abbasov@icloud.com>
>>> wrote:
>>>
>>>> Hi Ted,
>>>> sorry forget to mention
>>>>
>>>> release of hbase / hadoop you're using
>>>>
>>>> hbase hbase-0.98.7-hadoop2, hadoop hadoop-2.5.1
>>>>
>>>> were region servers doing compaction ?
>>>>
>>>> I’ve run major compactions manually earlier today, but it seems that
>>>> they already completed, looking at the compactionQueueSize.
>>>>
>>>> have you checked region server logs ?
>>>>
>>>> The logs of datanode is full of this kind of messages
>>>> 2015-09-02 16:37:06,950 INFO
>>>> org.apache.hadoop.hdfs.server.datanode.DataNode.clienttrace: src: /
>>>> 10.10.8.55:50010, dest: /10.10.8.54:32959, bytes: 19673, op:
>>>> HDFS_READ, cliID: DFSClient_NONMAPREDUCE_1225374853_1, offset: 0, srvID:
>>>> ee7d0634-89a3-4ada-a8ad-7848217327be, blockid:
>>>> BP-329084760-10.32.0.180-1387281790961:blk_1075277914_1540222, duration:
>>>> 7881815
>>>>
>>>> p.s. we had to change the ip addresses of the cluster nodes, is it
>>>> relevant?
>>>>
>>>> Thanks.
>>>>
>>>> On 02 Sep 2015, at 18:20, Ted Yu <yuzhihong@gmail.com> wrote:
>>>>
>>>> Please provide some more information:
>>>>
>>>> release of hbase / hadoop you're using
>>>> were region servers doing compaction ?
>>>> have you checked region server logs ?
>>>>
>>>> Thanks
>>>>
>>>> On Wed, Sep 2, 2015 at 9:11 AM, Akmal Abbasov <akmal.abbasov@icloud.com
>>>> > wrote:
>>>>
>>>>> Hi,
>>>>> I’m having strange behaviour in hbase cluster. It is almost idle, only
>>>>> <5 puts and gets.
>>>>> But the data in hdfs is increasing, and region servers have very high
>>>>> iowait(>100, in 2 core CPU).
>>>>> iotop shows that datanode process is reading and writing all the time.
>>>>> Any suggestions?
>>>>>
>>>>> Thanks.
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>>
>
>
> --
>
> *Adrien Mogenet*
> Head of Backend/Infrastructure
> adrien.mogenet@contentsquare.com
> (+33)6.59.16.64.22
> http://www.contentsquare.com
> 50, avenue Montaigne - 75008 Paris
>
>
>


-- 

*Adrien Mogenet*
Head of Backend/Infrastructure
adrien.mogenet@contentsquare.com
(+33)6.59.16.64.22
http://www.contentsquare.com
50, avenue Montaigne - 75008 Paris

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