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From Benjamin Black...@b3k.us>
Subject Re: Overwhelming a cluster with writes?
Date Tue, 06 Apr 2010 07:19:43 GMT
OK, cool, looking forward to your results.

On Tue, Apr 6, 2010 at 12:18 AM, Ilya Maykov <ivmaykov@gmail.com> wrote:
> Right, I meant 4GB heap vs. the standard 1GB. And all other options in
> cassandra.in.sh at their defaults.
>
> Sorry I am a bit new to JVM tuning, and very new to Cassandra :)
>
> -- Ilya
>
> On Tue, Apr 6, 2010 at 12:16 AM, Benjamin Black <b@b3k.us> wrote:
>> I am specifically suggesting you NOT use a heap that large with your
>> 8GB machines.  Please test with 4GB first.
>>
>> On Tue, Apr 6, 2010 at 12:13 AM, Ilya Maykov <ivmaykov@gmail.com> wrote:
>>> That does sound similar. It's possible that the difference I'm seeing
>>> between ConsistencyLevel.ZERO and ConsistencyLevel.ALL is simply due
>>> to the fact that using ALL slows down the writers enough that the GC
>>> can keep up. I could do a test with multiple clients writing at ALL in
>>> parallel tomorrow. If there are still no problems writing at ALL even
>>> with extra load from additional clients, that might point to problems
>>> in how async writes are handled vs. sync writes.
>>>
>>> I will also do some profiling of the server processes with both ZERO
>>> and ALL writer behaviors and report back.
>>>
>>> RE: JVM_OPTS, I will try running with the "more sane" options (but a
>>> larger heap) as well.
>>>
>>> -- Ilya
>>>
>>> On Mon, Apr 5, 2010 at 11:59 PM, Rob Coli <rcoli@digg.com> wrote:
>>>> On 4/5/10 11:48 PM, Ilya Maykov wrote:
>>>>>
>>>>> No, the disks on all nodes have about 750GB free space. Also as
>>>>> mentioned in my follow-up email, writing with ConsistencyLevel.ALL
>>>>> makes the slowdowns / crashes go away.
>>>>
>>>> I am not sure if the above is consistent with the cause of #896, but the
>>>> other symptoms ("I inserted a bunch of data really fast via Thrift and GC
>>>> melted my machine!") sound like it..
>>>>
>>>> https://issues.apache.org/jira/browse/CASSANDRA-896
>>>>
>>>> =Rob
>>>>
>>>
>>
>

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