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From "Fournier, Camille F." <Camille.Fourn...@gs.com>
Subject RE: swap
Date Mon, 13 Jun 2011 13:37:27 GMT
My advice is to turn off disk swap completely if you are using the machine to run only ZK,
or any app which should always have its entire heap in memory. Disk swapping by java heaps
is very, very bad for apps with performance driven by caching all state. You will need to
leave some amount of memory for OS overhead (it's been too long since I did that analysis
but I would make sure it is at least in the neighborhood of 10% of the total available memory).


-----Original Message-----
From: Donna Li [mailto:donna.li@utstar.com] 
Sent: Monday, June 13, 2011 3:09 AM
To: user@zookeeper.apache.org
Subject: 答复: swap

Thanks ted.
I want to know the relation between java heap size and swap. Zookeeper physical memory is
enough, but swap is used by 302064k. Should I increase my java heap size or decrease my java
heap size?

发件人: Ted Dunning [mailto:ted.dunning@gmail.com] 
发送时间: 2011年6月13日 14:33
收件人: user@zookeeper.apache.org
主题: Re: swap

This sounds like a question with a story behind it.

Do you mean that your ZK server filled up all of memory and caused the
machine to start swapping?

If that is your problem, then there really is no fix other than to not
do that.  The reason is that Zookeeper is memory based so if you don't
have enough memory, either because you are over-filling Zookeeper or
have insufficient memory, then things aren't going to work.

Turning off swap may be one of the worst things to do in this case
since the machine will tend to fail harder instead of just getting
very slow.  That can make recovery more difficult.

On Mon, Jun 13, 2011 at 5:52 AM, Donna Li <donna.li@utstar.com> wrote:
> Hi, all:
>        How to avoid swap on zookeeper server?
> Best Regards
> Donna li
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