Challenges in Cloud Computing – VM Migration


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Survey on Virtual Machine migration with in the intra-LAN network as well as the long distance migration.

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  • Applications of VMUse different OS’Software testing
  • Challenges in Cloud Computing – VM Migration

    1. 1. Challenges in Cloud Computing – VM Migration Sarmad Makhdoom 2012-03-0019 Kamran Khalil 2012-03-0012 Hafeez ur Rehman 2012-03-0031
    2. 2. Introduction
    3. 3. Cloud Computing • Cloud computing is an umbrella term used to refer to Internet based development and services • A number of characteristics define cloud data, applications services and infrastructure: ▫ ▫ ▫ Remotely hosted: Services or data are hosted on remote infrastructure. Ubiquitous: Services or data are available anywhere. Commodified: The result is a utility computing model similar to traditional that of traditional utilities, like gas and electricity - you pay for what you would want!
    4. 4. Virtual Machines • A virtual machine provides interface identical to underlying bare hardware ▫ i.e. all devices, interrupts, memory, page tables etc. • Applications of Virtual Machines • Virtualization Software ▫ ▫ ▫ ▫ VMWare ZAP Xen QEMU
    5. 5. Virtual Machines in Cloud ▫ Benefits of Virtual Machines       Virtualization help making efficient use of hardware resources Facilitates a greater degree of abstraction Easily move from one piece of hardware to another Replicate them at will Create more scalable and flexible infrastructure Snapshots ▫ Cloud computing has taken that degree of efficiency and agility realized from virtualization  Pooled resources  Geographic diversity  Universal connectivity
    6. 6. Research Problems
    7. 7. Research Problems • Automated services provisioning • Virtual machine migration • • • • • • • Server consolidation Energy management Traffic management and analysis Data security Software frameworks Storage technology and data management Novel cloud architecture
    8. 8. Motivation
    9. 9. Motivation • Consider a data center consisting of “n” physical machines (PM) hosting “m” VMs implementing one customer application each • Resources(CPU, Network, Memory, I/O) are allocated to each VM to handle the workload and operate at certain performance level (SLA) • Each VM sees workload fluctuation from time to time => resource requirement changes # of user visit increases PM Capacity VM1 VM2 cricinfo Network Bandwidth Memory CPU mail server Virtualization Layer Hardware Resource Allocation VM1 N = 5Gbps M = 8GB C = 4 cores = 10 Gbps = 16 GB = 8 cores VM2 N = 5Gbps M = 8GB C = 4 cores
    10. 10. Motivation • An increase in workload can be handled by allocating more resources to it, if idle resources are available • Main Issues: ▫ What if PM does not have (enough or no) idle resources to satisfy VM's requirement?  Performance of the application degrades  SLA violation occurs • Key Ideas ▫ Replication VMs ▫ Migrating VMs
    11. 11. Virtual Machine Migration It is impossible or impractical to bring the data (or devices) close to the computation engines.
    12. 12. Virtual Machine Migration • Why we need migration? • When we need to migrate? • How migration is done? • Issues in long distance migration (across data centers)
    13. 13. When we need to migrate? [NSDI’ 07] • Hotspots can cause SLA violations ▫ Burden on some Virtual or Physical Machines are called hotspots • Hotspot Detection (Sandpiper) ▫ Black-box Monitoring  CPU (/proc)  Network (/proc/net/dev)  Memory (swap) ▫ Gray-box Monitoring  Gather OS level statistics and application logs • A hotspot is flagged only if thresholds or SLAs are exceeded for a sustained time Wood T et al (2007) Black-box and gray-box strategies for virtual machine migration. In: Proc of NSDI
    14. 14. Gathering resource usage statistics Gathers on that server processor, network Determine: What virtual servers should migrate Monitors usage profiles to detect Where to move them hotspots. Construct resource much any resource exceeds a the How Hotspot: of a resource to allocate usage profiles forvirtual servers afterviolation) for a sustain threshold(or SLA migration each virtual server period (Predict PM workload) and memory swap statistics for each VM Implements a daemon to gather OS-level statistics and application logs Wood T et al (2007) Black-box and gray-box strategies for virtual machine migration. In: Proc of NSDI 14
    15. 15. When we need to migrate? [FGCS’ 12] • SLA violation detection ▫ Mapping low-level resource metrics to high-level SLAs ▫ Crude data maps to user requirements such as  CPU speed maps to Response Time  Occupied memory size maps to number of concurrent clients ▫ Predictive Strategy for detection of possible SLA violations ▫ Detection interval  Short measurement intervals may degrade performance  Long measurement intervals may cause ignorance of heavy SLA violations Towards autonomic detection of SLA violations in Cloud infrastructures, Future Generation Computer Systems, 2012
    16. 16. How migration is done? • Memory Migration ▫ Pre-copy  Push phase  Stop-and-copy phase  Pull Phase ▫ Pure demand-migration • File System Migration ▫ In case of distributed file system, there is no need to copy ▫ Alternatively, copy only changed local files to the destination using Virtual Machine Manager’s API. S. Venkatesha, S. Sadhu, S. Kintali, and S. Barbara, "Survey of virtual machine migration techniques" - Memory, 2009
    17. 17. How migration is done? • Network Migration ▫ If both source and destination are on same LAN switch  an unsolicited ARP reply from the migrating host is provided ▫ Alternatively, on a switched network  the migrating OS can keep its original Ethernet MAC address, relying on the network switch to detect its move to a new port • Device Migration ▫ Three type of device support  Emulation  Virtualization  Non-migratable S. Venkatesha, S. Sadhu, S. Kintali, and S. Barbara, "Survey of virtual machine migration techniques" - Memory, 2009
    18. 18. Migration: A Performance Evaluation • Testbed specification ▫ ▫ ▫ ▫ ▫ 6 Servers (1 head node, 5 VM hosts) Intel Xeon (2.33 GHz Quad-core with 2x6MB L2 Cache) 4GB memory and 7200rpm hard drive 64-bit Ubuntu Linux 8.04 Server Edition Apache 2.2.8 and MySQL 5.2.4-2 • Workload ▫ Olio as a Web 2.0 application ( ▫ Faban Load generator ( • Experiments ▫ 10 minute and 20 minute benchmark runs with 600 concurrent users Cost of virtual machine live migration in clouds: A performance evaluation, International Conference on Cloud Computing, 2009
    19. 19. Migration: A Performance Evaluation Cost of virtual machine live migration in clouds: A performance evaluation, International Conference on Cloud Computing, 2009
    20. 20. Migration across data centers • Need for VM mobility across data centers ▫ ▫ ▫ ▫ Data center maintenance without downtime Disaster avoidance Data center migration/expansion Workload balancing across multiple sites • Issues ▫ ▫ ▫ ▫ RTT is 1,000 times greater than sub-networks, ‘word wide wait’ Trust to a remote execution environment Interoperability at the level of Web Services, Java etc Migration across multiple domains are vulnerable to security exploits
    21. 21. Related Work: Migration over MAN/WAN [FGCS’06] • Introduced an intermediate traffic controller to facilitate migration which consists of: ▫ VM Traffic Controller  Provisioning of network resources and the re-provisioning of the IP tunnel to ensure seamless layer ▫ AAA (Authentication, Authorization and Accounting)  Pre-allocation of extra VM-resources required for migration ▫ DRAC (Dynamic Resource Allocation Controller)  Exposes a service-oriented API for coupling with applications ▫ Preservation of TCP and higher-level sessions  Dynamically configured IP tunnels allow client connectivity “Seamless Live Migration of Virtual Machines over the MAN/WAN”, Elsevier Future Generation Computer Systems 2006
    22. 22. Related Work: HP Cluster Extension and Microsoft Hyper-V™ • HP Cluster Extension (CLX) provides flawless mirroring capabilities for disaster recovery • VM data is already replicated in single data center cluster ▫ Modifications to spread it across multi-site:  Multi-site Disaster Recovery solution is implemented  CLX enables Hyper-V Live Migration across sites (VMware, Hyper-V, HP-VM and AMD-V) Our limitation is non-availability of peer referenced or published material of these architectures to discuss their techniques in detail
    23. 23. Proposed Solution • Security ▫ Layer 2 Link Encryption (IEEE 802.1AE) may be used to help ensure privacy and confidentially ▫ Token based security - Authorization message sequence to thwart resource theft • 1,000 times rise in RTT doesn’t matter much because ▫ All states will be transferred before the switch ▫ Downtime will be based on the time required in redirection  Which is only 5-10 times than the intra-LAN setup
    24. 24. Conclusion
    25. 25. Conclusion • Virtual machine migration provide significant benefits in cloud computing • State of the art work is already done on resource monitoring, live VM migration over the LAN and MAN/WAN • Downtime is 60ms to 3s which they assume is negligible • Small transient spikes does not trigger needless migrations, if threshold or SLAs are exceeded for sustained time • A slowdown is expected due to cache warm-up at the destination after migration • Hybrid approach has been suggested to harness the benefits of all technqiues