Hi.
I'm testing OpenStack setup set on our hardware with Fuel 6.0 and I found the
problem with 10Gbit network interfaces configuration.
Our setup uses Centos on deployed nodes - I didn't look how this situation
looks from Ubuntu perspective, but looking on the fuel-library - there is
probably the same effect.
With default settings, nodes deployed by fuel have 2.6.32.xxx linux kernel,
with 3.10 available and marked as "experimental".
Under webui for deployment, network interfaces are correctly shown as running
on 10Gbit, but... Maximal transfer rates which We could achieve were around
2.5Gbit/s.
After some investigation I found that interfaces configured by
/etc/sysconfig/network-scripts/ifcfg-* have set default MTU, no matter if
particular interface is or is not 10Gbit. I did not searched how other than
igxbe drivers works, but this particular under so old kernels in 10Gbit
configuration requires MTU set to at least 9000 (to turn on jumbo frames -
probably other drivers have similar requirement), to work properly.
Manual adding (this is only simplification, this should be set more carefully):
for f in /etc/sysconfig/network-scripts/ifcfg-* ; do echo "MTU=9000" >>$f ;
done
partially resolves this problem (partially, because under default 2.6.32.xxx
still We do not have better than 6Gbit/s transfers in single stream, but
situation is much better under mentioned above 3.10 kernel - We have full
10Gbit/s).
Looking into fuel-library, l23network::l3::ifconfig have ability to also
configure MTU, but this functionality looks unused in this situation.
End user which buys setup with 10Gbit/s 82599 based network adapters expects
that in default configuration "all should work as expected". From user
perspective - actual situation is faulty.
For this moment - not only in time of deploy he must select option marked as
"experimental", but also he must patch deployed setup, and remember to patch in
same way every one added in future physical node.
So, what We can do to make end user happier?
Could We in puppet files do something like:
if interface_link == '10Gbit' and interface_driver == 'igxbe':
set_mtu(9000)
interface_driver could be readed from link name, from
/sys/class/net/<devname>/device/driver/module
interface_link could be readed from ethtool <devname> | grep Speed
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