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From Jonathan Colby <jonathan.co...@gmail.com>
Subject Re: nodetool move hammers the next node in the ring
Date Sat, 09 Apr 2011 08:29:16 GMT
thanks!  I'll be watching this issue closely.

On Apr 9, 2011, at 5:41 AM, Chris Goffinet wrote:

> We also have a ticket open at 
> 
> https://issues.apache.org/jira/browse/CASSANDRA-2399
> 
> We have observed in production the impact of streaming data to new nodes being added.
We actually have our entire dataset in page cache in one of our clusters, our 99th percentiles
go from 20ms to >1 second on streaming nodes when bootstrapping in new nodes because of
blowing out the page cache during the process. We are hoping to have this addressed soon.
I think throttling of streaming would be good too, to help minimize saturating the network
card on the streaming node. Dynamic snitch should help with this, we'll try to report back
our results very soon on what it looks like for that case.
>  
> -Chris
> 
> On Apr 8, 2011, at 7:35 PM, aaron morton wrote:
> 
>> My brain just started working. The streaming for the move may need to be throttled,
but once the file has been received the bloom filters, row indexes and secondary indexes are
built. That will also take some effort, do you have any secondary indexes? 
>> 
>> If you are doing a move again could you try turing up logging to DEBUG on one of
the neighbour nodes. Once the file has been received you will see a message saying "Finished
{file_name}. Sending ack to {remote_ip}". After this log message the rebuilds will start,
 would be interesting to see what is more heavy weight I'm guessing the rebuilds.
>> 
>> This is similar to https://issues.apache.org/jira/browse/CASSANDRA-2156 but that
ticket will not cover this case. I've added this use case to the comments, please check there
if you want to follow along.
>> 
>> Cheers
>> Aaron
>> 
>> 
>> On 6 Apr 2011, at 16:26, Jonathan Colby wrote:
>> 
>>> thanks for the response Aaron.   Our cluster has 6 nodes with 10 GB load on each.
  RF=3.    AMD 64 bit Blades, Quad Core, 8 GB ram,  running Debian Linux.  Swap off.  Cassandra
0.7.4
>>> 
>>> 
>>> On Apr 6, 2011, at 2:40 AM, aaron morton wrote:
>>> 
>>>> Not that I know of, may be useful to be able to throttle things. But if the
receiving node has little head room it may still be overwhelmed.
>>>> 
>>>> Currently there is a single thread for streaming. If we were to throttle
it may be best to make it multi threaded with a single concurrent stream per end point. 
>>>> 
>>>> Out of interest how many nodes do you have and whats the RF?
>>>> 
>>>> Aaron
>>>> 
>>>> 
>>>> On 6 Apr 2011, at 01:16, Jonathan Colby wrote:
>>>> 
>>>>> 
>>>>> When doing a move, decommission, loadbalance, etc.  data is streamed
to the next node in such a way that it really strains the receiving node - to the point where
it has a problem serving requests.   
>>>>> 
>>>>> Any way to throttle the streaming of data?
>>>> 
>>> 
>> 
> 


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