RE: [Xen-users] XEN - networking and performance

[Simon Hobson <simon@xxxxxxxxxxxxxxxx>]

Jeff Sturm wrote:

> One of the traps we've run into when virtualizing moderately 
> I/O-heavy hosts, is not sizing our disk arrays right.  Not in terms 
> of capacity (terabytes) but in spindles.  If each physical host 
> normally has 4 dedicated disks, for example, virtualizing 8 of these 
> onto a domU attached to a disk array with 16 drives effectively cuts 
> that ratio from 4:1 down to 2:1.  Latency goes up, throughput goes 
> down.
Not only that, but you also guarantee that the I/O is across 
different areas of the disk (different partitions/logical volumes) 
and so you also virtually guarantee a lot more seek activity.
--
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

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