[Openstack] Network speed issue

Georgios Dimitrakakis giorgis at acmac.uoc.gr
Tue Dec 16 17:23:38 UTC 2014

 Hi all!

 In my OpenStack installation (Icehouse and use nova legacy networking) 
 the VMs are talking to each other over a 1Gbps network link.

 My issue is that although file transfers between physical (hypervisor) 
 nodes can saturate that link transfers between VMs reach very lower 
 speeds e.g. 30MB/s (approx. 240Mbps).

 My tests are performed by scp'ing a large image file (approx. 4GB) 
 between the nodes and between the VMs.

 I have updated my images to use e1000 nic driver but the results remain 
 the same.

 What are any other limiting factors?

 Does it has to do with the disk driver I am using? Does it play 
 significant role the filesystem of the hypervisor node?

 Any ideas on how to approach the saturation of the 1Gbps link?

 Best regards,


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