I have several xensource servers running lots of PV-On-HVM Windows
DomUs and I have a pretty weird problem. Here are my details:
Kernel: 3.5.0-rc2
OpenvSwitch module: Built-in from upstream (aka did not install kernel
module when building OpenvSwitch)
OpenvSwitch userland tools: version 1.4.0
I have a single Bridge with two fake-bridges.
I have configured a LACP bond with 4 physical nics that connects to a
PortChannel on a 6509.
I setup the native vlan on the 6509 to be 102.
I have configured the bond with vlan_mode=native-untagged and tag=102.
All my vms are added to the fake-bridge associated with vlan 102.
I have four servers configured this way all connected to the same 6509,
ServerA, ServerB, ServerC, and ServerD.
I have no problem sending and receiving traffic to any VM on any of the
four servers, in other words all my VMs get IPs from a DHCP Server and
can icmp each other.
I have decent performance moving files, SMB2, from VMs that are on
different servers, aka VM1 on ServerA copies a file to VM2 on ServerB.
I have horrible performance when moving files, SMB2, from VMs that are
on the same server, aka VM1 on ServerA copies a file to VM2 on ServerA.
I am not an expert on how OpenvSwitch works, and I can't discount that
my own stupidity may be behind this, but I am at a loss for what to do
to troubleshoot this.
I have captured packets of a reproducible type or session of network
traffic, aka Logging into a VM with the same account which has a roaming
profile configured. This pulls down about 50MB of data and when logging
into a VM that is on a different server than the file server that hosts
the profile it takes about 11 seconds. When logging into a VM that is
on the same server as the file server it takes well over 20 minutes and
never really succeeds.
What I can see that is different from the two packet captures are the
amount of retransmits, Duplicate ACKs and Out-of-Order packets are
insane when going from vm to vm on the same server.
It seems to me after looking at the traffic in the capture that
everything is trucking along until we get to a large file, say 5MB, then
it just falls apart. On the VM that is on a different server, I can get
the file moved across in only 458 packets, with only 36 TCP ACKed lost
segment packets flagged.
On the VM that is on the same server, I can't get the file moved across
even after 6800+ packets, with 5500 Dup ACKs, Out-of-Order or
retransmission packets flagged.
There has to be something going on that could explain this, but I am at
a loss! Any help would be greatly appreciated!!
Mike
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