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From Ilya Maykov <>
Subject Re: Overwhelming a cluster with writes?
Date Tue, 06 Apr 2010 07:18:51 GMT
Right, I meant 4GB heap vs. the standard 1GB. And all other options in 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 <> 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 <> 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 <> 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..
>>> =Rob

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