[one-users] Shared storage performance

Andreas Calvo andreas.calvo at scytl.com
Thu Jun 21 01:55:42 PDT 2012

We are facing a performance issue in our opennebula infrastructure, and 
I'd like to heard your opinion on the best approach to solve it.

We have 15 nodes plus 1 front-end. They all have the same shared storage 
thru iscsi, and they mount the opennebula home folder (/var/lib/one) 
which is a GFS2 partition.
All machines are based on CentOS 6.2, using QEMU-KVM.

We use the cloud to perform tests against a 120 VMs farm.

As we are using QCOW2, it really decreases the need to write changes to 

However, all machines need to copy over 1G of data every time they 
start, and this really collapse our iscsi network, until some machines 
receive a timeout accessing to data which stops the test.
Opennebula infrastructure suffers from a read/write penalty leaving some 
VMs in pending state and the system (almost) non-responsive.

We are not using at all the local disk of the nodes.

It seems that the only option is to use the local disk to write disk 
changes, but I wanted to know what's your experienced opinion on our 


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