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Re: [Xen-devel] Blktap device monitoring code!

On Fri, 2009-11-20 at 20:29 -0500, Ata E Husain wrote:
> Dear All,


> I am trying to get details with respect to the disk accesses (read/writes) 
> done by domUs by putting some monitoring code in dom0. One way to achieve 
> this is to create all domUs in separate  LVM and use some disk monitoring 
> utility program like iostat to get the details, but is it possible to get 
> the details without running any utility program such as putting some 
> monitoring code in hypervisor to do the required ?

The hypervisor is quite definitely the wrong place as it doesn't do
peripheral I/O virtualization.

> I am using a tap:aio configuration to mount by domU image, and am going 
> through blktap device driver files to get some details but till now no luck.

You could hook into the dom0 kernel. There are ways to do so with or
without xen, but since  I/O virtualization can forward block I/O
requests to userspace, blktap is probably exactly what you want.

Look into tools/blktap2 and the block-log driver. IIRC it's only logging
writes right now (?). Anyway, it should get you started.


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