Re: [Xen-users] Xen questions - Swap, networking and errors

["M.A. Williamson" <maw48@xxxxxxxxx>]

> This is my first time trying Xen.  I have installed Xen-2.0.6, on a
> Debian Sarge server.  I have a few questions that I haven't been able to
> find answers to in the documentation or FAQs.
OK, welcome to the community! I'll try and answer your questions. If 
there's anything you feel should be in a FAQ, feel free to get a Wiki 
account and add it at http://wiki.xensource.com.
> 1)When I boot xen0, the specified amount of RAM shows up in top
> correctly, but the swap partitions I have are not activated.  When I
> attempt to activate swap myself, I recieve the following error message:
>         xen:/# swapon /dev/hde2
>         swapon: /dev/hde2: No such device or address
> The server has a mirrored RAID1 setup, and both MD devices are detected
> and mounted properly.  However, I am confused about why the kernel does
> not see the hard disk partitions themselves.  The disks are SATA drives,
> and so at first I thought perhaps it didn't recongize the drives, but if
> that were the case, I don't think either MD device would be detected
> properly.  Is there a boot option that I have not seen to address this
Are all the drives in the machine the same? Are other partitions on hde in 
the RAID configuration.
If the drives are on different controllers (e.g. a couple of PATA and a 
SATA, as on some systems) then the default kernel config may not be 
building the drivers for hde but still builds enough drivers for the MD 
devices to work.
> As a side note, what is a proper amount of RAM needed for xen0?  I have
> not found any documentation really stating how much RAM is need for the
> priveledged Xen instance.  The server itself has 4GB of RAM.  Should
> xen0 have all 4GB of RAM to partition to the xenU domains?
RAM that you give to dom0 can't be allocated to domUs. 256MB should 
probably be enough for a slim dom0. If you use LVM snapshots that'll need 
to be larger though.
You can use the "balloon driver" to reduce the size of dom0 after booting 
if you need more memory for other domains.
> 2)With the default xend config, when I start xend the bridge device
> xen-br0 is created.  However, after that I lose all network activity to
> xen0.  I noticed that no vif devices were created, only xen-br0.
> Initially, xen-br0 doesn't have an IP.  I've tried setting it to the IP
> of eth0, and a 192.168.0.x IP, but I still cannot get networking up.
Sounds a bit broken... What should happen is that eth0's IP is transferred 
to xen-br0.
Do you have any existing bridge setup? Anything else unusual in your 
networking config?
> I changed the xend config to use the network-route rather than network,
> and when I start xend, networking doesn't go down, but xen-br0 is not
> created.  I am not sure why the default network config is not working.
> Do I need to make changes to the routing tables?
You won't get a xen-br0 if you're using the routed config - you don't need 
it. Don't know about the routing tables as I've never used the routed 
config myself.
<snip>
> ioctl: LOOP_SET_FD: Device or resource busy
<snip>
> vif-route up vif=vif1.0 domain=TestDomain mac=aa:00:00:62:e9:12
> I am not sure why the error message LOOP_SET_FD: Device or resource busy
> appears, since the loopback device I created the root filesystem on is
> not mounted or being used.
What does ls -l /dev/loop* give you?

Cheers,
Mark

> I have attached my xend-config and xenU config that appears to be
> crashing.  Any help that can be offered is appreciated, especially links
> to documentation that I might have missed.
>
> Regards,
>
> Dan Lang
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