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Re: [Xen-users] copying or dding from a VM-template resulting in the who

To: ma qiang <maqiang1984@xxxxxxxxx>
Subject: Re: [Xen-users] copying or dding from a VM-template resulting in the whole system getting stuck
From: "Fajar A. Nugraha" <list@xxxxxxxxx>
Date: Fri, 15 Oct 2010 08:48:59 +0700
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Delivery-date: Thu, 14 Oct 2010 18:50:14 -0700
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On Thu, Oct 14, 2010 at 9:50 AM, ma qiang <maqiang1984@xxxxxxxxx> wrote:
Hi all,
     When I create a new VM by copying or dding from a VM-template, the cp/dd operation takes almost all the memory and gets one cpu rate to almost 100%, resulting in the whole system getting stuck. 

Takes all the memory? How do you determine that?
anyone knows how to perform this with less cost?

In common x86 systems today, disk (throughput and IOPS) is usually the bottleneck. Try ionice, something like

ionice -n 7 -c 2 dd if= ....

it should lower disk I/O priority for the dd process, giving room for other process.

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