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From Oleg Dulin <oleg.du...@gmail.com>
Subject Re: Unbalanced ring mystery multi-DC issue with 1.1.11
Date Fri, 27 Sep 2013 12:01:04 GMT
Here is some more information.

I am running full repair on one of the nodes and I am observing strange 
behavior.

Both DCs were up during the data load. But repair is reporting a lot of 
out-of-sync data. Why would that be ? Is there a way for me to tell 
that WAN may be dropping hinted handoff traffic ?

Regards,
Oleg

On 2013-09-27 10:35:34 +0000, Oleg Dulin said:

> Wanted to add one more thing:
> 
> I can also tell that the numbers are not consistent across DRs this way 
> -- I have a column family with really wide rows (a couple million 
> columns).
> 
> DC1 reports higher column counts than DC2. DC2 only becomes consistent 
> after I do the command a couple of times and trigger a read-repair. But 
> why would nodetool repair logs show that everything is in sync ?
> 
> Regards,
> Oleg
> 
> On 2013-09-27 10:23:45 +0000, Oleg Dulin said:
> 
>> Consider this output from nodetool ring:
>> 
>> Address         DC          Rack        Status State   Load            
>> Effective-Ownership Token
>> 
>> 127605887595351923798765477786913079396
>> dc1.5      DC1 	RAC1        Up     Normal  32.07 GB        50.00%       0
>> dc2.100    DC2 RAC1        Up     Normal  8.21 GB         50.00%        100
>> dc1.6      DC1 RAC1        Up     Normal  32.82 GB        50.00%        
>> 42535295865117307932921825928971026432
>> dc2.101    DC2 RAC1        Up     Normal  12.41 GB        50.00%        
>> 42535295865117307932921825928971026532
>> dc1.7      DC1 RAC1        Up     Normal  28.37 GB        50.00%        
>> 85070591730234615865843651857942052864
>> dc2.102    DC2 RAC1        Up     Normal  12.27 GB        50.00%        
>> 85070591730234615865843651857942052964
>> dc1.8      DC1 RAC1        Up     Normal  27.34 GB        50.00%        
>> 127605887595351923798765477786913079296
>> dc2.103    DC2 RAC1        Up     Normal  13.46 GB        50.00%        
>> 127605887595351923798765477786913079396
>> 
>> I concealed IPs and DC names for confidentiality.
>> 
>> All of the data loading was happening against DC1 at a pretty brisk 
>> rate, of, say, 200K writes per minute.
>> 
>> Note how my tokens are offset by 100. Shouldn't that mean that load on 
>> each node should be roughly identical ? In DC1 it is roughly around 30 
>> G on each node. In DC2 it is almost 1/3rd of the nearest DC1 node by 
>> token range.
>> 
>> To verify that the nodes are in sync, I ran nodetool -h localhost 
>> repair MyKeySpace --partitioner-range on each node in DC2. Watching the 
>> logs, I see that the repair went really quick and all column families 
>> are in sync!
>> 
>> I need help making sense of this. Is this because DC1 is not fully 
>> compacted ? Is it because DC2 is not fully synced and I am not checking 
>> correctly ? How can I tell that there is still replication going on in 
>> progress (note, I started my load yesterday at 9:50am).


-- 
Regards,
Oleg Dulin
http://www.olegdulin.com



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