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?
>>>
>>
>
