RE: [Xen-users] copying or dding from a VM-template resulting in the whole system getting stuck

[Jeff Sturm <jeff.sturm@xxxxxxxxxx>]

I’d consider 64KB reasonable.   If you don’t give a block size on the dd command however, expect the copy to take a long time.

 

From: ma qiang [mailto:maqiang1984@xxxxxxxxx]
Sent: Friday, October 15, 2010 2:18 AM
To: Jeff Sturm
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] copying or dding from a VM-template resulting in the whole system getting stuck

 

Thanks a lot. It works much better.

By the way, what is the reasonable buffer size. I have tested many based on different computers, and shows different results.

 

On Thu, Oct 14, 2010 at 9:17 PM, Jeff Sturm <jeff.sturm@xxxxxxxxxx> wrote:

This on Linux?  I find copying image files with O_DIRECT is helpful.

 

With the “dd” command, try “iflag=direct” and “oflag=direct”.  Use a reasonable buffer size, like bs=64k or so, to achieve a faster copy operation.

 

-Jeff

 

From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of ma qiang
Sent: Wednesday, October 13, 2010 10:51 PM

To: xen-users@xxxxxxxxxxxxxxxxxxx

Subject: [Xen-users] copying or dding from a VM-template resulting in the whole system getting stuck

 

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. 

anyone knows how to perform this with less cost?

 

Thanks a lot.

Qiang

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