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). 

C

-----Original Message-----
From: Donna Li [mailto:[email protected]] 
Sent: Monday, June 13, 2011 3:09 AM
To: [email protected]
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?

-----邮件原件-----
发件人: Ted Dunning [mailto:[email protected]] 
发送时间: 2011年6月13日 14:33
收件人: [email protected]
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 <[email protected]> wrote:
>
> Hi, all:
>        How to avoid swap on zookeeper server?
>
> Best Regards
> Donna li
>

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