Re: [Xen-users] DomU network dies

["Fajar A. Nugraha" <fajar@xxxxxxxxx>]

On Fri, Sep 3, 2010 at 2:17 AM, Olav Lavell <olav@xxxxxxxxx> wrote:
> Just to be clear, should I apply the ethtool-command to the eth0 interface
> or to the peth0 and/or vif1.0 on the Dom0?

haven't done that in a while, so I forgot the details. Should be
peth0, and (probably) eth0.

>> The thing I'm not sure Debian is the "best" distro for people like
>> you, who like to use the distro's packages and would like it to "just
>> work". I'd actually recommend you simply use Centos5. Others on this
>> list have suggested Opensuse 11.3, but with updated kernel from
>> opensuse kotd. Or even Fedora 13, with third-party RPMs.
>
> Why, exactly? I am comfortable with Debian in general. It's just Xen that
> I need to become more familiar with (I'm on my way, if just slowly). But if
> there is something inherently broken in Debian's Xen I would like to know
> of course.

Debian is using pv_ops kernel version. Which is good, in a way, since
that's where upstream Xen developers are concentrating their efforts
on. But that also means big changes, which leads to possible bugs.
Apparently you got one of them. CMIIW, I don't think Debian guys by
themselves are doing much to fix xen-related bugs, relying on
upstream.

Novell (Opensuse and SLE) uses the old xenfied linux version,
forward-ported to newer kernels. Andrew Lyon picked xen-related
changes from Novell's kernel and make it available as a patch for
vanilla kernel on
http://code.google.com/p/gentoo-xen-kernel/downloads/list . I've had
better luck with this kernel version, and currently using it on dev
environment.

RHEL5 uses an "old" version of Xen and kernel,  but they actively
maintain it with bug/security fixes, so it's been very stable.

So from bugs/stability point of view, I'd really recommend using
RHEL/Centos and their built-in Xen version, with Novell's kernel as an
alternative if you need newer kernel version.

>
>> If you're willing to compile from source, you can use latest Xen and
>> pv_ops kernel. See http://wiki.xensource.com/xenwiki/Xen4.0 ,
>> tutorials section in particular.
>
> I would rather not, too lazy to manage updates etc.

... which is another reason why I think you'd be better of using RHEL/Centos.

>
>>> But will I be able to just copy my
>>> DomU files (images and configuration) over to the "older" version and
>>> still use them?
>>
>> Should be possible, regardles of what your dom0 distro is.
>
> OK, thanks. I worried perhaps Xen 4 uses different image formats or
> something. It is good to know I have the option of downgrading. I
> understand Debian Lenny + Xen 3 is a tried and tested combination that
> shouldn'g give me too much trouble.

Newer versions of libvirt uses xend-managed config file by default
(which is in sxp format), but they can read old-style config just
fine. And you can convert sxp-style config to old-style config file
(for easier reading, if you want) easily with the help of virsh.
There might be some difference in default bridge name, but that can
quickly be edited on domU config file.


>
> Meanwhile, to keep my server going I made a little monitoring script that
> executes every 5 minutes from cron on the Dom0. It pings the DomU and when
> it doesn't get a reply, writes a line to a log file and reboots the whole
> machine. Ugly but effective.

If you're willing to reboot the whole machine just to make it work,
then I highly suggest you spend some time to at least compiling your
own kernel with xen patches above. If it works for you, then at least
you still get to keep Debian (only changing the kernel).

-- 
Fajar

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