Before we start• Get    involved!• If   you use Twitter, feel free to tweet about this session (use  hashtag #tovmug)•I en...
Elastic vSphere:Now with More StretchExamining the design considerations for buildingstretched VMware vSphere clusters    ...
Agenda•A   quick review of stretched clusters• Stretched   cluster considerations• Looking   forward• Questions   and answ...
StretchedCluster ReviewA quick review of vSphere stretched clusters
Stretched Cluster Review• Sometimes    referred to as a “split cluster”•A  stretched cluster is a cluster with ESX/ESXi ho...
Stretched Cluster Review• HA/DRS   are not required in a stretched cluster, although they are typically deployed• Many pro...
StretchedCluster ConsiderationsExamining some considerations on the use of stretchedvSphere clusters
Stretched ClusterConsiderations: vMotion• Stretched   clusters are not a prerequisite for long-distance vMotion• However, ...
Stretched ClusterConsiderations: Storage• Active/active   data centers require read/write storage at both ends  • Storage ...
Stretched ClusterConsiderations: Storage• One   solution is the stretched SAN solution • Stretching the SAN fabric between...
Stretched ClusterConsiderations: Storage• Another   solution is distributed virtual storage • Distributes   storage in a r...
Stretched ClusterConsiderations: Storage
Stretched ClusterConsiderations: Storage     VM            R/W          Storage
Stretched ClusterConsiderations: Storage                     VM          R/W        Storage
Stretched ClusterConsiderations: Storage                            VM                    R/W                  Storage
Stretched ClusterConsiderations: HA• vSphere   HA can provide cross-site failover• However,   vSphere HA is not currently ...
Stretched ClusterConsiderations: HA• InvSphere 4.x, no more than 8 hosts in HA-enabled stretched clusters or you’ll run af...
Stretched ClusterConsiderations: DRS• You   can balance load across sites using vSphere DRS• However,   vSphere DRS (like ...
Stretched ClusterConsiderations: Storage DRS• vSphere    5 introduces Storage DRS• Like   vSphere DRS, Storage DRS is not ...
Stretched ClusterConsiderations: Networking• Stretched   clusters add some networking complexity  • More complex network c...
Stretched ClusterConsiderations: Networking   Router                    Router                 L2 Tunnel            VM
Stretched ClusterConsiderations: Networking   Router                    Router                 L2 Tunnel            VM
Stretched ClusterConsiderations: Networking   Router                     Router             L2 Tunnel                     ...
Stretched ClusterConsiderations: Networking   Router                     Router             L2 Tunnel                     ...
Stretched ClusterConsiderations: Operations• Movement of VMs between sites (perhaps due to HA/DRS) could impact other area...
LookingForward…What will the future bring? Some speculation on the future ofstretched vSphere clusters
The Future ofStretched Clusters• HA/DRSare simultaneously “greatest strength and greatest weakness” for stretched clusters...
The Future ofStretched Clusters• Stretched          clusters will benefit from further networking developments such as:  •...
The Future ofStretched Clusters• Improvements     in storage functionality will help stretched clusters • Active/active   ...
Questions &Answers
Thank You
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Elastic vSphere, Now With More Stretch

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I gave this presentation at the Toronto VMUG on September 27, 2011. The presentation is an update of my previous stretched cluster presentations, with new content for vSphere 5.

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  • Elastic vSphere, Now With More Stretch

    1. 1. Before we start• Get involved!• If you use Twitter, feel free to tweet about this session (use hashtag #tovmug)•I encourage you to take photos or videos of today’s session and share them online• Thispresentation will be made available online after the event
    2. 2. Elastic vSphere:Now with More StretchExamining the design considerations for buildingstretched VMware vSphere clusters Scott Lowe, VCDX 39 vExpert, Author, Blogger, Geek http://blog.scottlowe.org / Twitter: @scott_lowe
    3. 3. Agenda•A quick review of stretched clusters• Stretched cluster considerations• Looking forward• Questions and answers
    4. 4. StretchedCluster ReviewA quick review of vSphere stretched clusters
    5. 5. Stretched Cluster Review• Sometimes referred to as a “split cluster”•A stretched cluster is a cluster with ESX/ESXi hosts in different physical locations, usually different geographic sites• Stretched clusters are typically built as a way to create “active/active” data centers in order to: • Provide high availability across sites • Do dynamic workload balancing across sites
    6. 6. Stretched Cluster Review• HA/DRS are not required in a stretched cluster, although they are typically deployed• Many pros and cons of stretched clusters stem directly from the use of HA/DRS• Stretched clusters are not a requirement for long-distance vMotion
    7. 7. StretchedCluster ConsiderationsExamining some considerations on the use of stretchedvSphere clusters
    8. 8. Stretched ClusterConsiderations: vMotion• Stretched clusters are not a prerequisite for long-distance vMotion• However, vMotion does derive from benefit from stretched clusters: • Intra-cluster vMotions are highly parallelized • Inter-cluster vMotions are serial• Usinga stretched cluster could offer benefits to disaster avoidance use cases
    9. 9. Stretched ClusterConsiderations: Storage• Active/active data centers require read/write storage at both ends • Storage performance suffers otherwise • Storage vMotion required to fix the performance hit• There are a couple different ways of addressing this requirement; each approach has its benefits/drawbacks• Solutions are generally limited to synchronous (~100km) distances
    10. 10. Stretched ClusterConsiderations: Storage• One solution is the stretched SAN solution • Stretching the SAN fabric between locations will usually involve multiple VSANs and inter-VSAN routing • Typically read/write in one location (read-only in the other) • Cross-connect topology allows hosts on both side to access read/write storage but introduces multipathing considerations• Implementations with only a single storage controller at each location create a SPoF (single point of failure)
    11. 11. Stretched ClusterConsiderations: Storage• Another solution is distributed virtual storage • Distributes storage in a read/write fashion across multiple sites • Uses data locality algorithms to maximize cache benefits • Typically uses multiple controllers in a scale-out fashion • Needs a clustered file system for simultaneous host access• Must address “split brain” scenarios
    12. 12. Stretched ClusterConsiderations: Storage
    13. 13. Stretched ClusterConsiderations: Storage VM R/W Storage
    14. 14. Stretched ClusterConsiderations: Storage VM R/W Storage
    15. 15. Stretched ClusterConsiderations: Storage VM R/W Storage
    16. 16. Stretched ClusterConsiderations: HA• vSphere HA can provide cross-site failover• However, vSphere HA is not currently “site aware” • You can’t control failover destination • You can’t designate or define things like: • Per-site failover capacity • Per-site failover hosts • Per-site admission controls
    17. 17. Stretched ClusterConsiderations: HA• InvSphere 4.x, no more than 8 hosts in HA-enabled stretched clusters or you’ll run afoul of HA primary node limitations • Can only deploy 4 hosts or less per site per cluster • Ensures distribution of HA primary nodes • No supported method to increase the number of primary nodes or to specify HA primary nodes• vSphere5 has a new HA architecture that eliminates this consideration
    18. 18. Stretched ClusterConsiderations: DRS• You can balance load across sites using vSphere DRS• However, vSphere DRS (like HA) is not “site aware”• DRS host affinity rules can mimic “site awareness” • DRS host affinity rules are not dynamic • DRS host affinity rules create administrative overhead • DRS host affinity rules are defined and managed on a per- cluster basis
    19. 19. Stretched ClusterConsiderations: Storage DRS• vSphere 5 introduces Storage DRS• Like vSphere DRS, Storage DRS is not “site aware”• Manually align datastore clusters with storage topology to avoid introducing unnecessary latency• User-defined storage capabilities and profile-driven storage could be used to help mimic site awareness• Watch for impact on storage replication/synchronization
    20. 20. Stretched ClusterConsiderations: Networking• Stretched clusters add some networking complexity • More complex network configuration is required to provide Layer 2 adjacency (or its equivalent) • More complex networking required to address routing issues created by VM mobility • Technologiesto address these concerns are new (OTV, LISP) and require networking expertise to configure and maintain• What about the virtual network design?
    21. 21. Stretched ClusterConsiderations: Networking Router Router L2 Tunnel VM
    22. 22. Stretched ClusterConsiderations: Networking Router Router L2 Tunnel VM
    23. 23. Stretched ClusterConsiderations: Networking Router Router L2 Tunnel VM
    24. 24. Stretched ClusterConsiderations: Networking Router Router L2 Tunnel VM
    25. 25. Stretched ClusterConsiderations: Operations• Movement of VMs between sites (perhaps due to HA/DRS) could impact other areas: • Backups • Personnel/support • Disaster recovery/replication • Performance of multi-tier applications
    26. 26. LookingForward…What will the future bring? Some speculation on the future ofstretched vSphere clusters
    27. 27. The Future ofStretched Clusters• HA/DRSare simultaneously “greatest strength and greatest weakness” for stretched clusters• vSphere 5 improves the situation significantly• Stretched clusters would directly benefit from improvements to HA/DRS in these areas: • “Site awareness” • More scalable/dynamic DRS host affinity rule management (policy-based placement)
    28. 28. The Future ofStretched Clusters• Stretched clusters will benefit from further networking developments such as: • LISP (or equivalent) to decouple network routing from network identity • OTV, EoMPLS, or other equivalents to enable Layer 2 adjacency • Not yet clear how VXLAN will play in this space• In the longer-term future, the need for Layer 2 adjacency needs to be addressed and resolved
    29. 29. The Future ofStretched Clusters• Improvements in storage functionality will help stretched clusters • Active/active read-write storage at greater distances • Better handling of “split brain” scenarios • Better/more direct integration with replication for topologies with >2 sites (Sync-Sync-Async, for example)
    30. 30. Questions &Answers
    31. 31. Thank You

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