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Date: Thu, 20 Oct 2011 15:38:02 +0200
From: Maxim Potekhin <potekhin@bnl.gov>
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To: user@cassandra.apache.org
CC: aaron morton <aaron@thelastpickle.com>
Subject: Re: CMS GC initial-mark taking 6 seconds , bad?
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Hello Aaron,

I happen to have 48GB on each machines I use in the cluster. Can I 
assume that I can't really use all of this memory productively? Do you 
have any suggestion related to that? Can I run more than one instance on 
Cassandra on the same box (using different ports) to take advantage of 
this memory, assuming the disk has enough bandwidth?

Thanks,
Maxim

On 9/25/2011 11:37 AM, aaron morton wrote:
> It does seem long and will be felt by your application.
>
> Are you running a 47GB heap ? Most peeps seem to think 8 to 12 is about the viable maximum.
>
> Cheers
>
> -----------------
> Aaron Morton
> Freelance Cassandra Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> On 25/09/2011, at 7:14 PM, Yang wrote:
>
>> I see the following in my GC log
>>
>> 1910.513: [GC [1 CMS-initial-mark: 2598619K(26214400K)]
>> 13749939K(49807360K), 6.0696680 secs] [Times: user=6.10 sys=0.00,
>> real=6.07 secs]
>>
>> so there is a stop-the-world period of 6 seconds. does this sound bad
>> ? or 6 seconds is OK  and we should expect the built-in
>> fault-tolerance of Cassandra handle this?
>>
>> Thanks
>> Yang