hbase-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Chris Tarnas <...@email.com>
Subject Re: data loss due to regionserver going down
Date Wed, 27 Jul 2011 16:40:38 GMT
That is strange behavior. How long did you wait between Step 2 and 3, and what is the results
of running

hbase hbck 

at step 3?

-chris

On Jul 27, 2011, at 9:23 AM, 吴限 wrote:

> Thx for your reply. But actually later I did another experiment similar to
> one which I explained earlier.
> Step 1: I inserted some data into the hbase.
> Step 2: I shut one of the region servers.
> Step 3 : I checked the table and found some data had been lost.
> Step 4: I disabled the table and then enabled the table
> Step 5 : I checked again and found nothing lost.
> 
> If some data didn't exist in the other region server, then how can u explain
> this?
> 
> Hope to get ur reply.Thx~
> 
> 2011/7/28 Chris Tarnas <cft@email.com>
> 
>> Replication of 1x means no replication. 2x would mean the data exists in
>> two locations (what it looks like you want). Running with a replication of
>> 1x is a very bad idea and is pretty much a guaranteed way to get data loss.
>> 
>> -chris
>> 
>> On Jul 27, 2011, at 8:58 AM, 吴限 wrote:
>> 
>>> Hi everyone. I'd like to run the following *data* *loss* scenario by you
>> to
>>> see if
>>> we are doing something obviously wrong with our setup here.
>>> 
>>> Setup:
>>>  -cdh3u0
>>>  - Hadoop 0.20.2
>>>  - HBase 0.90.1
>>>  - 1 Master Node running as NameNode & JobTracker
>>>  -zookeeper quorum
>>>  - 2 child nodes running as Datanode, TaskTracker and RegionServer each
>>>  - dfs.replication is set to 1
>>> 
>>> First, I inserted some data into the hbase a few hours ago.
>>> Then after a while. I rebooted one of the region servers and waited until
>>> the master responded to that. However, after I checked the table using
>> hbase
>>> shell (I used the "count" command), I noticed that there was a huge
>> amount
>>> of data being lost.
>>> After I restarted the regionserver which I had rebooted and checked
>> again,
>>> I found that some of the missing data was got back but there still
>> existed
>>> some data which hadn't been found yet.
>>> At last,after I disabled the table and then enabled the table , I found
>> that
>>> all data was stored in the cluster and there was no data that was lost.
>>> 
>>> This is problematic since we are supposed to
>>> replicate at x1, so at least one other node should be able to
>>> theoretically serve the *data* that the downed regionserver can't.
>>> 
>>> Questions:
>>> 
>>>  - How can you guys explain this weird situation?
>>>  - Are there way to recover such lost *data*?
>>> 
>>> Any tips here are definitely appreciated. I'll be happy to provide more
>>> information as well.-0
>> 
>> 


Mime
View raw message