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RE: [Xen-users] Consolidating machines using xen

Just wanted to pipe in and say that the burning aspect is easily achieved.  Block device exports may not allow it, but a iscsi setup will (try rocketdivision iscsi for windows for good support of remote dvd-rw/ram).


However, I don’t think anybody has managed a usefull domu+pciback+x setup, some have come close (myself included), but nothing really useable.


From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Christopher Isip
Sent: July 12, 2008 11:13 PM
To: James Pifer
Cc: Xen List
Subject: Re: [Xen-users] Consolidating machines using xen



On Sat, Jul 12, 2008 at 8:51 PM, James Pifer <jep@xxxxxxxxxxxxxxxx> wrote:

On Sat, 2008-07-12 at 20:40 -0400, James Pifer wrote:
> I've been using xen at work for several months and pretty happy with it.
> I'm currently running several machines at home and I'm thinking about
> picking up some new hardware and consolidating them.
> The machines I have are:
> myth backend on FC9

I dont think it is possible to have s FC9 domU at this point.  From what I've read, it is in transition and pciback is not working.  I have tried an FC8 domU but I couldn't get pciback working there as well.  I have an Ubuntu 8.04 domU running mythbackend and that seems to be working fine except for ivtv DMA timeouts here and there in dmesg.  I am not sure that the DMA timeouts are a xen issue though.   I am hoping that someone will come up with an error free mythbackend domU setup using pvr 250s and pvr 500s one day and post how they did it.  Also, you will need to play with swiotlb a bit to get everything working.  Increasing swiotlb memory allowed me to increase mpeg buffer memory as well to prevent dropped frames from "Not reading fast enough" errors.  


> myth frontend on MythDora (FC8)

You can run a mythfrontend in dom0.  The newest nvidia drivers will compile in a xen kernel if you specify a particular environment variable.  Go a bit further and load up on nvidia specific driver options in xorg.conf to reduce xorg cpu usage to near zero.  I just figured this out the other night.  If you need the info, I can post it here.  I managed to reduce xorg cpu utilization to <10 %.  I tried to setup a mythfrontend domU but couldn't get it to work. I have a geforce card as well and you will get as far as compiling and loading the nvidia kernel module but as soon as you start mythfrontend, the screen flickers and you get a memory error.  I think others have tried as well and encountered the same roadblock.

> mail/dns/dhcp/web server on FC5 (I know, old...)

Will work fine in domUs.  I haven't tried an internet accessible webserver yet. I use centos 5.1 for dns/dhcp and ubuntu for qmail.  All of my domUs have their own webservers. Also try a separate mysql server just for fun.

> multi-purpose/storage machine (FC9)

I have pcibacked a combo SATA/PATA pci express card and exported it via nfs.  This is running in the mythbackend domU.  In my case, it was necessary as the jmicron card will not run in dom0 (dmesg reports it as disabled) possibly because It conflicts with my onboard SATA/IDE controller. 

> Windows XP machine - some windows utils, Nero burning, etc

I believe you need VT enabled hardware for this.

> Some of these would need direct access to PCI cards. mythtv needs access
> to three tuner cards.
> Not sure I would try the myth frontend machine. Could I have a domU have
> direct access to a specific video card? (nvidia fx5200)
> Windows XP would need direct access to DVD-RW drives. Or at least be
> able to use them as writers. Possible?
> Of course I have to get the "boss" to approve, but I'm thinking about
> this hardware:
> Motherboard:
> http://www.ecost.com/Detail/MOTHERNOARDS/GIGA-BYTE/GA-P35-S3G/40399167.aspx
> Processor:
> http://www.ecost.com/Detail/Processors/Intel/BX80562Q6600/34990428.aspx
> Then I would add a couple SATA hard drives and 4 gig of RAM (2x2048),
> allowing for an additional 4 gig later.
> Am I nuts or could this work?

Oh yeah, couple things I forgot. What about sound and USB devices from
domU's? Not something I even think about in my work environment.

This can be done as well.  I have pcibacked usb devices (/sbin/lspci devices) for use in domUs.  So far I have managed to get usb printers working, an X10 usb automation device, a bluetooth usb device.  I've also used a usb to parallel port and usb to serial port device in a domU.  Only the usb printers needed a bit of tweakage and I could only get it to work in a Centos domU.  You will have to have the source kernel installed and edit usblp.c to reduce memory from 8192 to 4096, recompile usblp and use that to replace the current module. The information is on  a list somewhere.  Also , it seems that late pciback binding is not possible for usb devices.  Therefore, you will have to create a initrd which preloads pciback.

Good Luck.  Please post your successful configuration.  I would love to hear from other mythtv xen users.  I dont think there are very many of us out there.



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