How to find dom0 name from hosted domU

xen

I'm actually testing RHEL 5.3 with Xen between two servers in order to have a disaster recovery solution. So I'm playing with moving my domU from one dom0 server to the other server.

Unfortunatly when somebody else move the domU I don't have any clue where my domain is hosted.
I'm wondering where I can't find my dom0 name with inside domU. I'm looking for something like the gzonename command on a solaris sparse zone.
I check inside /proc/xen but I don't see anything special except the dom0 kernel release.

Does anybody know a wait to find this ?

Best Answer

We use xenstore-write /tool/hostname $(uname -n); xenstore-chmod /tool/hostname r on Dom0 and then xenstore-read /tool/hostname within the VMs. Easy and lightweight ...

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Based on the information you've provided so far I would suggest that problem is with the MAC address duplication and the disconnections may be from the switch you're ethernet port is going through.

That said there will be some MAC address duplication. I just checked on one of my Xen servers that I have been working on and I get the following when I run ifconfig | grep HWaddr

eth0      Link encap:Ethernet  HWaddr 00:E0:81:2D:66:AC  
eth1      Link encap:Ethernet  HWaddr 00:E0:81:2D:66:AD  
peth0     Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
peth1     Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
vif0.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
vif0.1    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
vif31.0   Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
vif31.1   Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
virbr0    Link encap:Ethernet  HWaddr 00:00:00:00:00:00  
xenbr0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
xenbr1    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF

This is on a RHEL5 Xen 3.0.3 server so I am assuming the interface differences are based on changes between 3.0.3 and 3.1.2. That aside you can see that both my eth0 and eth1 interfaces are different MAC addresses whereas yours are both identical. the pethX and vifX.X entries are all virtual interfaces for Xen so the MAC address FE:FF:FF:FF:FF:FF is perfectly fine.

The xenbr0 is the bridge that eth0 is attached to and xenbr1 is the bridge for eth1 and use the same MAC address. The virbr0 interface is the bridge for the internal virtual network and has the 00:00:00:00:00:00 MAC because of having spanning tree protocol enabled. You can confirm the bridging on your system by running brctl show which should give you something like:

bridge name bridge id       STP enabled interfaces
virbr0      8000.000000000000   yes     
xenbr0      8000.feffffffffff   no  vif31.0
                            peth0
                            vif0.0
xenbr1      8000.feffffffffff   no  vif31.1
                            peth1
                            vif0.1

Linux – USB forwarding from dom0 to domU

I use Xen with USB passthrough to my domU on Centos5.

So far I can tell: Forward the complete USB-stuff or nothing. Do not try to forward only some OHCI/UHCI devices.

So here it runs more or less (haven't started a stress test yet):

Disconnect all USB devices
Unload the USB devices from dom0 via pciback. Unload UHCI/OHCI and EHCI devices. (Write some kind of init.d script for your needs). Details about pciback are here under point 1
Restart xend
lsusb should output nothing on dom0
edit you domU configuration file with the pci = [ '0000:yy:xx.0'] stuff
Start your domU
domU should report USB devices via lspci (other pciids) and lsusb

My dom0 is booted with kernel-parameter noirqdebug (grub).

Best Answer

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