CloudStack is one of many cloud orchestration platforms which can deliver IaaS clouds. One of the key capabilities of CloudStack is its ability to support multiple hypervisors in a CloudStack cloud. So whether your virtualization preference is VMware vSphere, KVM, Citrix XenServer or Linux Containers (LXC), you can build highly scalable clouds. While basic functionality is common across all hypervisors, many features are implemented differently on each. This paper presents the capabilities of CloudStack which can be enabled based on your hypervisor selection

1. Hypervisor Selection in Cloud
Understanding the choices available
CloudStack Collaboration Conference Europe 2013
Tim Mackey – XenServer Community Evangelist

2. Building a successful cloud
What are we trying to accomplish?

3. Service Offerings
• Clearly define what you want to offer
ᵒ What types of applications
ᵒ Who has access, and who owns them
ᵒ What type of access
• Define how templates need to be managed
ᵒ Operating system support
ᵒ Patching requirements
• Define expectations around compliance and availability
ᵒ Who owns backup and monitoring
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4. Define Tenancy Requirements
• Department data local to department
ᵒ Where is the application data stored
• Data and service isolation
ᵒ VM migration and host HA
ᵒ Network services
• Encryption of PII/PCI
ᵒ Where do keys live when data location unknown
ᵒ Need encryption designed for the cloud
• Showback to stakeholders
ᵒ More than just usage, compliance and audits
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5. Virtualization Infrastructure
• Hypervisor defined by service offerings
ᵒ
ᵒ
ᵒ
ᵒ
Don’t select hypervisor based on “standards”
Understand true costs of virtualization
Multiple hypervisors are “OK”
Bare metal can be a hypervisor
• To “Pool” resources or not
ᵒ Is there a real requirement for pooled resources
ᵒ Can the cloud management solution do better?
ᵒ Real cost of shared storage
• Primary storage defined by hypervisor
• Template storage defined by solution
ᵒ Typically low cost options like NFS
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6. The primary choices ….

7. XenServer
Guest
Guest
Driver front
Driver front
Standard Linux Distribution (dom0)
xapi
patches
Driver back
drivers
qemu
Xen Project Hypervisor
Compute
Networking
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Storage

8. KVM (Linux + KVM only)
Guest
Guest
Virtual driver
Virtual driver
libvirt
Standard Linux Distribution
KVM Module
agent
Compute
virtio
drivers
Networking
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qemu
Storage

9. vSphere 5.1 Managed by vCenter
Guest
Guest
Virtual driver
Virtual driver
Service
Console
vCenter
vmkernel
Task
Scheduler
vNIC
vSCSI
vmklinux
Compute
Networking
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drivers
Storage

10. Linux Containers
Namespace
Container
Namespace
Container
Cgroup
Cgroup
libvirt
Standard Linux Distribution
Namesspaces
Cgroups
Compute
Networking
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KVM Module
agent
Storage

11. Defining the network

12. Flat Network – Basic Layer 3 Network
Feature
XenServer
vSphere
KVM
LXC
Security Groups
Yes- bridge
No
Yes
Yes
IPv6
No
No
Yes
Yes
Multiple IPs per
NIC
Yes
Yes
Yes
Yes
Nicira NVP
Yes
No
Yes
No
BigSwitch VNS
Yes
No
Yes
Public Network
65.11.0.0/16
No
Security Group 1
65.11.1.2
65.11.1.3
65.11.1.4
65.11.1.5
DHCP,
DNS
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CloudStack
Virtual Router
Guest VM 1
Guest VM 2
Guest VM 3
Guest VM 4
Security Group 2

13. VLANs for Private Cloud
Feature
XenServer
vSphere
KVM
LXC
Max VLANs
800
254
1024
1024
IPv6
No
No
Yes
Yes
Multiple IPs per
NIC
Yes
Yes
Yes
Yes
Nicira NVP
Yes
No
Yes
No
BigSwitch VNS
Yes
No
Yes
No
MidoKura
No
No
Yes
No
VPC
Yes
Yes
Yes
Yes
Yes
Yes
Public
Network/Internet
Public IP
65.37.14.1
No
NetScaler
Guest Virtual Network 10.0.0.0/8
VLAN 100
No
F5 BigIP
Yes
Yes
Yes
No
Juniper SRX
No
Yes
Yes
No
Cisco VNMC
No
Yes
No
No
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CloudStack
Virtual Router
DHCP, DNS
NAT
Load Balancing
VPN
Gateway
10.1.1.1
10.1.1.1
10.1.1.3
10.1.1.4
10.1.1.5
Guest VM 1
Guest VM 2
Guest VM 3
Guest VM 4

14. Beyond the VLAN – Network Virtualization
Feature
XenServer
vSphere
KVM
LXC
OVS GRE tunnels
Yes
No
No
No
Nicira STT tunnel
Yes
No
Yes
No
MidoNet
No
No
Yes
No
VXLAN
No
Yes
No
No
NVGRE
No
No
No
No
Nexus 1000v
No
Yes
No
No
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15. Virtual Private Cloud and nTier Applications
Feature
PVLAN
XenServer
Yes - ovs
vSphere
Yes
KVM
ovs
LXC
No
DC2
DC1
DC3
VLAN 1
DC4
Web
S2S VPN
Router
VLAN 2
App
Private
GW
VLAN 3
DC5
DC6
DB
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16. Delivering specific network services
• IPv6  KVM is your only virtualized option (basic or advanced)
• Maximum VLANs  XenServer or KVM are your best options
• Security Groups  XenServer or KVM are your options
• VXLAN requires vSphere Enterprise Plus
• Cisco Nexus 1000v and ASA 1000v require vSphere Enterprise Plus
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17. Instances need a home
Storage, Storage and more Storage

18. Primary Storage Options
Feature
XenServer
vSphere
KVM
LXC
Local storage
Yes
Yes
Yes
Yes
NFS
Yes
Yes
Yes
Yes
Host
Single path iSCSI
Yes
Yes
Yes
No
Host
Multipath iSCSI
PreSetup
No
No
No
Direct array
No
VAAI
No
No
Shared Mount
No
No
Yes
Yes
Template format
VHD
OVA
QCOW2
TAR
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Primary Storage
Cluster

19. Core virtualization capabilities
The limits and features which matter

20. CloudStack Features
Feature
XenServer
vSphere
KVM
LXC
Disk IO Statistics
Yes
No
Yes
Memory Overcommit
Yes (4x)
Yes
No
No
Dedicated resources
Yes
Not with HA/DRS
Yes
No
Disk IO throttling
No
No
Yes
Yes
Disk snapshot (running)
Yes
Yes
No
No
Disk snapshot (Stopped)
Yes
Yes
Yes
No
Memory snapshot
Yes
Yes
Yes
No
Zone wide primary storage
No
Yes
Yes
Yes
Resize disk
Offline
Online Grow
Online
No
High availability
CloudStack
Native
CloudStack
No
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21. XenServer 6.2
Feature
Source code model
Open Source (GPLv2)
Maximum VM Density
650
CloudStack VM Density
150
CloudStack integration
Direct XAPI calls
Maximum native cluster Size
16
Maximum pRAM
1 TB
Largest VM
16vCPU/128GB
Windows Operating System
All Windows supported by Microsoft
Linux Operating Systems
RHEL, CentOS, Debian, Ubuntu, SLES, OEL
Advanced features supported
ovs, Storage XenMotion, DMC
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22. vSphere 5.1 (vSphere 5.5 not supported)
Feature
Source code model
Proprietary
Maximum VM Density
512
CloudStack VM Density
128
CloudStack integration
vCenter
Maximum native cluster Size
32
Maximum pRAM
2 TB
Largest VM
64 vCPU/1TB
Windows Operating Systems
DOS, All Windows Server/Client
Linux Operating Systems
Most
Advanced features supported
HA, DRS, DVS, Storage vMotion
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23. KVM (RHEL/CentOS 6.3 and Ubuntu 12.04)
Feature
Source code model
Open Source (GPLv2)
Maximum VM Density
10 times the number of pCores
CloudStack VM Density
50
CloudStack integration
CloudStack Agent (libvirt)
Maximum native cluster size
No native cluster support
Maximum pRAM
2 TB
Largest VM
Windows Operating Systems
Linux Operating Systems
Advanced features supported
None
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24. Linux Containers
Feature
Source code model
Open Source (GPLv2)
Maximum container Density
6000 (theoretical)
CloudStack container Density
50
CloudStack integration
CloudStack Agent (libvirt), requires KVM for SVMs
Maximum native cluster size
N/A
Maximum pRAM
2 TB
Largest container
2TB
Windows Operating Systems
N/A
Linux Operating Systems
Kernel compatible distros
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25. Picking the “best one”
When to use which hypervisor…

26. KVM
• Primary value proposition:
ᵒ Low cost with available vendor support
ᵒ Familiar administration model
ᵒ Broad CloudStack feature set with active development
• Cloud use cases:
ᵒ
ᵒ
ᵒ
ᵒ
Linux centric workloads
Dev/test clouds
Web hosting
Tenant density which dictates SDN options
• Weaknesses:
ᵒ Requires use of an installed CloudStack libvirt agent
ᵒ Limited native storage options
ᵒ No use of advanced native features
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27. Linux Containers
• Primary value proposition:
ᵒ Low cost with available vendor support
ᵒ Familiar administration model
• Cloud use cases:
ᵒ Dev/test clouds
ᵒ Web hosting
• Weaknesses:
ᵒ Requires use of an installed CloudStack libvirt agent
ᵒ Requires KVM for system VMs
ᵒ No use of advanced native features
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28. vSphere
• Primary value proposition:
ᵒ
ᵒ
ᵒ
ᵒ
ᵒ
Broad application and operating system support
Readily available pool of vSphere administration talent
Large eco-system of vendor partners
Many CloudStack features are native implementations
Direct feature integration via vCenter
• Cloud use cases:
ᵒ Private enterprise clouds
ᵒ Dev/test clouds
• Weaknesses:
ᵒ vSphere up-front license and ongoing support costs
ᵒ vCenter integration requires redundant designs
ᵒ Single data center per zone model
© Citrix 2013. More information at xenserver.org and follow me on twitter @XenServerArmy

29. XenServer
• Primary value proposition:
ᵒ
ᵒ
ᵒ
ᵒ
Low cost with available vendor support
Broad CloudStack feature set with active development
Large CloudStack install base
Direct integration via XAPI toolstack
• Cloud use cases:
ᵒ
ᵒ
ᵒ
ᵒ
ᵒ
Linux centric workloads
Dev/test clouds
Web hosting
Desktop as a Service clouds
Large VM and tenant
• Weaknesses:
ᵒ Minimal use of advanced native features
© Citrix 2013. More information at xenserver.org and follow me on twitter @XenServerArmy

30. What About Multiple Hypervisor Support?
• vSphere Datacenter must be contained within a single zone
• Force system VMs to a specific hypervisor type
• HA won’t migrate between hypervisors
• Zone wide primary storage doesn’t support multiple hypervisors
• Capacity planning at the cluster/pod level more difficult
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31. Work better. Live better.