misc. questions

[Mark Felder]

On Wed, 06 Mar 2013 14:17:02 -0600, Jay West <jwest at ezwind.net> wrote:

> 1)            One or two of our freebsd 9.1 HVM (with PVM drivers) under
> Xenserver 6.1 advanced are fairly frequently generating this message on  
> the
> console: xn_txeof: WARNING: response is -1! Any ideas what this may be  
> and
> what should be done? It does seem to only occur on the machines that have
> higher network load than the others.

You're having success with Xenserver 6.1? That's good news. I wonder why  
XCP 1.6 is unable to boot FreeBSD if there's an emulated DVDROM? :(

> 2)            We did a pilot project of about 8 VM's (the above mentioned
> environment) and all went well. Now that we've moved it into production  
> with
> many more VM's, I'm wondering about recommended tuning. I seem to recall
> from watching this list that there are a few sysctl's and the like that  
> are
> highly recommended, I think they had to do with network settings and  
> turning
> off "offloading" or somesuch. Does anyone have a quick & dirty list of
> "here's the first things you should always change" with regards to  
> FreeBSD
> HVM (pvm drivers) under XenServer?

If you're using pf, you will certainly need to set net.inet.tcp.tso=0

As far as the other offloading -- I put this on my NICs:

ifconfig_xn0="(your stuff here) -txcsum -rxcsum -lro -tso"

> 3)            When migrating bare-metal non-VM FreeBSD machines  
> (primarily
> webservers and mailservers) to the above Xenserver environment, we have
> always just created VM's from an ISO, installed apache, sendmail, etc.  
> and
> then migrated the websites, mailboxes, etc. manually "across the wire"  
> from
> the non-VM machines to the replacement VM's. Xenconvert does not seem to
> support FreeBSD/gpart/ufs. Does anyone know of a way (software or  
> procedure)
> to take a bare-metal FreeBSD 9.1 install and turn it into a VDI or  
> OVF/OVA
> that can be imported to Xenserver?

We usually install the same version on the VM and rsync the entire OS  
over. Then replace the kernel with the XENHVM one, do a bit of tweaking  
(rc.conf, pf.conf, fstab), and move on.

FYI, when we build kernels we do:

make buildkernel KERNCONF=XENHVM
make installkernel KERNCONF=XENHVM DESTDIR=/boot/ KODIR=9.1-XENHVM

This puts the kernel and modules in /boot/9.1-XENHVM and leaves the  
GENERIC kernel alone (as an emergency fallback)

/boot/loader.conf then contains kernel="9.1-XENHVM"

Note: for 9.0 it doesn't install the modules when you do it this way. We  
just set module_path="/boot/kernel;/boot/modules" and piggyback on the  
GENERIC kernel's modules.