KVM and Hylafax

KVM and Hylafax

[Federico Fanton]

Hi everyone!
We have an Hylafax 5.2.5 CentOS 5 installation hosted inside a Xen 
virtual machine. It works quite well, but now I'm in the process of 
upgrading/migrating it to a KVM virtual machine running Ubuntu 10.04.

The problem I'm having is that - while receiving works fine - sending 
faxes is extremely unreliable, I get lots of "No response to MPS 
repeated 3 tries", or "Failure to transmit clean ECM image data", just 
what would happen if the phone line was noisy.

Since the line, modem and configuration files I'm using are the same as 
before, I thought that it could be a KVM scheduling issue, but even 
setting cpu_shares to 10240 instead of 1024 doesn't change a thing...

I've tried asking on the Hylafax ML, and they say that

"generally speaking I'm very skeptical of real-time performance for 
virtualized machines and especially virtualized serial hardware. 
Because fax is time-sensitive it's certainly possible for the virtual 
machine to not be attentive-enough to it."

Are there any success stories on running Hylafax on KVM? What could I 
try to make it more "attentive"?


Here's how I'm mapping the serial port (where the modem is connected):

<serial type='dev'>
    <source path='/dev/ttyS0'/>
    <target port='0'/>
</serial>


And how I tuned the VM:

<cputune>
   <shares>10240</shares>
   <period>100000</period>
   <quota>-1</quota>
</cputune>


Many thanks for your time!

Re: KVM and Hylafax

[Michael]

On Thu, Mar 29, 2012 at 9:15 PM, Federico Fanton <federico@panizzolo.it> wrote:
> Hi everyone!
> We have an Hylafax 5.2.5 CentOS 5 installation hosted inside a Xen virtual
> machine. It works quite well, but now I'm in the process of
> upgrading/migrating it to a KVM virtual machine running Ubuntu 10.04.
>
> The problem I'm having is that - while receiving works fine - sending faxes
> is extremely unreliable, I get lots of "No response to MPS repeated 3
> tries", or "Failure to transmit clean ECM image data", just what would
> happen if the phone line was noisy.
>
> Since the line, modem and configuration files I'm using are the same as
> before, I thought that it could be a KVM scheduling issue, but even setting
> cpu_shares to 10240 instead of 1024 doesn't change a thing...
>
> I've tried asking on the Hylafax ML, and they say that
>
> "generally speaking I'm very skeptical of real-time performance for
> virtualized machines and especially virtualized serial hardware. Because fax
> is time-sensitive it's certainly possible for the virtual machine to not be
> attentive-enough to it."
>
> Are there any success stories on running Hylafax on KVM? What could I try to
> make it more "attentive"?
>
>
> Here's how I'm mapping the serial port (where the modem is connected):
>
> <serial type='dev'>
>   <source path='/dev/ttyS0'/>
>   <target port='0'/>
> </serial>
>
>
> And how I tuned the VM:
>
> <cputune>
>  <shares>10240</shares>
>  <period>100000</period>
>  <quota>-1</quota>
> </cputune>
>
>
> Many thanks for your time!
>
> --
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I've run hylafax under  KVM  in guest without any problems.
( not sure about configuration - since have no longer access to that site )
I think I've been using USB-2-serial adapter. and run kvm without libvirt



-- 
--
Michael

Re: KVM and Hylafax

[Federico Fanton]

On 29/03/2012 22:57, Michael wrote:

 > I've run hylafax under  KVM  in guest without any problems.
 > ( not sure about configuration - since have no longer access to that 
site )

Thanks, there's hope then :)

 > I think I've been using USB-2-serial adapter. and run kvm without libvirt

What do you mean, without libvirt? By calling qemu-kvm manually?

Re: KVM and Hylafax

[Federico Fanton]

>> We have an Hylafax 5.2.5 CentOS 5 installation hosted inside a Xen virtual
>> machine. It works quite well, but now I'm in the process of
>> upgrading/migrating it to a KVM virtual machine running Ubuntu 10.04.
>>
>> The problem I'm having is that - while receiving works fine - sending faxes
>> is extremely unreliable, I get lots of "No response to MPS repeated 3
>> tries", or "Failure to transmit clean ECM image data", just what would
>> happen if the phone line was noisy.

For the record, I switched to a CentOS VM instead of an Ubuntu one, and 
now it's working much better