Trying to understand BRITE files in CloudSim—the connectivity of brokers and datacentres
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Michael Kenning
Nov 9, 2018, 9:45:43 AM11/9/18
to CloudSim Plus
I am currently experimenting with the code in NetworkExample3.java and the topology.brite file that comes with the simulation software.
The line highlighted in red gives a warning that Vm 0/Broker 3 is unable to be assigned to Datacenter 1, presumably because Vm 1/Broker 4 is already assigned to its single host. Instead, it allocates the VM to Datacenter 2.
Here's the output from the execution of the programme (note that it hangs while waiting for the cloudlet result):
I wanted to understand how the edges affect the allocation of VMs to hosts in the datacentres. The node connectivity at the moment looks like this:
(Ignore the direction of the arrows; initially I thought the edges were directed, but apparently they aren't.)
In NetworkExample3, two brokers are set up along with two datacentres. Each datacentre contains one host. Each broker has one cloudlet to assign. When the simulation is finished, the cloudlets will have been executed each on a separate datacentre.
In the above picture, nodes 0 and 2 correspond to Datacenters 1 and 2 respectively; nodes 3 and 4 correspond to Brokers 3 and 4 respectively.
This is the output of a run:
Starting NetworkExample3
INFO Starting CloudSim Plus 4.0.4INFO DatacenterSimple1 is starting...INFO DatacenterSimple2 is starting...INFO DatacenterBrokerSimple3 is starting...INFO DatacenterBrokerSimple4 is starting...INFO Entities started.INFO 0.0: DatacenterBrokerSimple3: List of 2 datacenters(s) received.INFO 0.0: DatacenterBrokerSimple3: Trying to Create Vm 0/Broker 3 in DatacenterSimple1INFO 0.0: DatacenterBrokerSimple4: List of 2 datacenters(s) received.INFO 0.0: DatacenterBrokerSimple4: Trying to Create Vm 1/Broker 4 in DatacenterSimple1INFO 3.0: VmAllocationPolicySimple: Vm 1/Broker 4 has been allocated to Host 0/DC 1WARN 3.9: VmAllocationPolicySimple: No suitable host found for Vm 0/Broker 3 in Datacenter 1INFO 6.1: DatacenterBrokerSimple4: Sending Cloudlet 1 to Vm 1/Broker 4 in Host 0/DC 1.INFO 6.1: DatacenterBrokerSimple4: All waiting Cloudlets submitted to some VM.INFO 7.9: DatacenterBrokerSimple3: Trying to Create Vm 0/Broker 3 in DatacenterSimple2 (due to lack of a suitable Host in previous one)INFO 12.9: VmAllocationPolicySimple: Vm 0/Broker 3 has been allocated to Host 0/DC 2INFO 18.0: DatacenterBrokerSimple3: Sending Cloudlet 0 to Vm 0/Broker 3 in Host 0/DC 2.INFO 18.0: DatacenterBrokerSimple3: All waiting Cloudlets submitted to some VM.INFO 172.1: DatacenterBrokerSimple4: Cloudlet 1 finished and returned to broker.INFO 188.0: DatacenterBrokerSimple3: Cloudlet 0 finished and returned to broker.INFO 188.0: Processing last events before simulation shutdown.INFO 188.0: DatacenterBrokerSimple3 is shutting down...INFO 188.0: DatacenterBrokerSimple3: Requesting Vm 0/Broker 3 destruction.INFO 188.0: DatacenterBrokerSimple4 is shutting down...INFO 188.0: DatacenterBrokerSimple4: Requesting Vm 1/Broker 4 destruction.INFO 191.00: DatacenterSimple: Vm 1/Broker 4 destroyed on Host 0/DC 1.
INFO 193.00: DatacenterSimple: Vm 0/Broker 3 destroyed on Host 0/DC 2.
INFO Simulation: No more future events
INFO CloudInformationService0: Notify all CloudSim Plus entities to shutdown.
INFO 193.0: DatacenterSimple1 is shutting down...INFO 193.0: DatacenterSimple2 is shutting down...INFO ================== Simulation finished at time 193.00 ==================
Broker DatacenterBrokerSimple3
Cloudlet|Status |DC|Host|Host PEs |VM|VM PEs |CloudletLen|CloudletPEs|StartTime|FinishTime|ExecTime ID| |ID| ID|CPU cores|ID|CPU cores| MI| CPU cores| Seconds| Seconds| Seconds----------------------------------------------------------------------------------------------------- 0|SUCCESS| 2| 0| 1| 0| 1| 40000| 1| 23| 183| 160-----------------------------------------------------------------------------------------------------
Broker DatacenterBrokerSimple4
Cloudlet|Status |DC|Host|Host PEs |VM|VM PEs |CloudletLen|CloudletPEs|StartTime|FinishTime|ExecTime ID| |ID| ID|CPU cores|ID|CPU cores| MI| CPU cores| Seconds| Seconds| Seconds----------------------------------------------------------------------------------------------------- 1|SUCCESS| 1| 0| 1| 1| 1| 40000| 1| 9| 169| 160-----------------------------------------------------------------------------------------------------NetworkExample3 finished!
Process finished with exit code 0
The line highlighted in red gives a warning that Vm 0/Broker 3 is unable to be assigned to Datacenter 1, presumably because Vm 1/Broker 4 is already assigned to its single host. Instead, it allocates the VM to Datacenter 2.
This is perfectly comprehensible from what I can see in the BRITE file. Broker 4 (node 4) is connected to both datacenters. Broker 3 is connected directly to 0 and indirectly (via nodes 0 and 4) to 2.
Experimentation
I decided to experiment with the BRITE file to test the effects on the programme. I removed all edges except for those connecting (1) node 3/Broker 3 to node 0/Datacenter 1, and (2) node 4/Broker 4 to node 2/Datacenter 2.
I expected to see Broker 3 assign its VM to Datacenter 1 and Broker 4 to assign its VM to Datacenter 2, without further ado. I expect this because this is how I've specified the connections in the BRITE file.
However, this is not what I see when I run the code; instead it hangs. Here's the modified topology.brite file:
Topology: ( 5 Nodes, 8 Edges )
Model (1 - RTWaxman): 5 5 5 1 2 0.15000000596046448 0.20000000298023224 1 1 10.0 1024.0
Nodes: ( 5 )
0 1 3 3 3 -1 RT_NODE
1 0 3 3 3 -1 RT_NODE
2 4 3 3 3 -1 RT_NODE
3 3 1 3 3 -1 RT_NODE
4 3 3 4 4 -1 RT_NODE
Edges: ( 8 )
1 3 0 2.8284271247461903 3.9 10.0 -1 -1 E_RT U
2 4 2 1.0 4.0 10.0 -1 -1 E_RT U
Starting NetworkExample3INFO Starting CloudSim Plus 4.0.4INFO DatacenterSimple1 is starting...INFO DatacenterSimple2 is starting...INFO DatacenterBrokerSimple3 is starting...INFO DatacenterBrokerSimple4 is starting...INFO Entities started.INFO 0.0: DatacenterBrokerSimple3: List of 2 datacenters(s) received.INFO 0.0: DatacenterBrokerSimple3: Trying to Create Vm 0/Broker 3 in DatacenterSimple1INFO 0.0: DatacenterBrokerSimple4: List of 2 datacenters(s) received.INFO 0.0: DatacenterBrokerSimple4: Trying to Create Vm 1/Broker 4 in DatacenterSimple1INFO 3.9: VmAllocationPolicySimple: Vm 0/Broker 3 has been allocated to Host 0/DC 1INFO 7.9: DatacenterBrokerSimple3: Sending Cloudlet 0 to Vm 0/Broker 3 in Host 0/DC 1.INFO 7.9: DatacenterBrokerSimple3: All waiting Cloudlets submitted to some VM.INFO 175.70000000000002: DatacenterBrokerSimple3: Cloudlet 0 finished and returned to broker.WARN 1.7976931348623157E308: VmAllocationPolicySimple: No suitable host found for Vm 1/Broker 4 in Datacenter 1INFO Infinity: DatacenterBrokerSimple4: Trying to Create Vm 1/Broker 4 in DatacenterSimple2 (due to lack of a suitable Host in previous one)INFO Infinity: VmAllocationPolicySimple: Vm 1/Broker 4 has been allocated to Host 0/DC 2INFO Infinity: DatacenterBrokerSimple4: Sending Cloudlet 1 to Vm 1/Broker 4 in Host 0/DC 2.INFO Infinity: DatacenterBrokerSimple4: All waiting Cloudlets submitted to some VM.
Both brokers try to submit their cloudlets to the datacenters as above. This time, however, Broker 4 attempts to allocate its VM to the other datacenter. This time however it fails. This makes no sense to me, given that Broker should have a direct connection to the second Datacenter.
This error can be fixed adding an additional edge between any other pair of nodes—i.e., between 0 and 4, 2 and 3, or 3 and 4.
Question
Why do I not see my expected output? Is there something missing in my understanding of the BRITE file and the way that CloudSim Plus uses them?
LAHIAOUNI ABDERRAHMAN
Nov 13, 2018, 5:16:05 AM11/13/18
to clouds...@googlegroups.com
Hello Michael,
In the first scenario, if the 1 host in the first data center had enough resources to host both Vms it would have, in the second scenario i see that both Vms were allocated as you said, but it is saying infinity, ill try to explain this:
1-The brite file doesn't affect policies in any way it just define bandwidth and latencies between nodes.
2-As a result of the first point if 2 nodes try to communicate there should be an edge in Brite linking them if there is non you will experience the hanging, like the broker 4 trying to allocate its Vm to Dc1 in 2nd scenario but failed and took so much time
1.7976931348623157E308 since there is no edge between node 0 and 4 it means there is 0 bandwidth between them (this is how the simulator works) so the time to transfer a message between the 2 will be infinite.3-An info to note in your brite file with those 2 edges there it is not possible to have spanning tree, i.e if there was an edge between 3 and 2 there would be an indirect connection between 4 and 0 and your example would have worked since the cloudsim (this existed since original cloudsim) is capable of finding indirect routes in the topology graph.4- I repeat that your Brite never affects "default" policies unless you write some on your own that take its content in consideration.Best regards.
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