Module: Business Continuity

Transcription

1 Upon completion of this module, you should be able to: Describe business continuity and cloud service availability Describe fault tolerance mechanisms for cloud infrastructure Discuss data protection solutions Describe the key design strategies for cloud application resiliency 1

2 Cloud Computing Reference Model Business Continuity Cross-layer Function 2

3 Lesson: Business Continuity Overview This lesson covers the following topics: Business continuity Cloud service availability Causes of service unavailability Impact of cloud service unavailability Key methods to achieve the required cloud service availability 3

4 What is Business Continuity? Business Continuity BC entails preparing for, responding to, and recovering from service outage that adversely affects business operations. BC enables continuous availability of cloud services in the event of failure Helps to meet the required service level BC involves various proactive and reactive measures Disaster recovery is a part of BC, which coordinates the process of restoring infrastructure, including data Required to support ongoing cloud services, after a disaster occurs 4

5 Cloud Service Availability Cloud Service Availability Refers to the ability of a cloud service to perform its agreed function according to business requirements and customer expectations during its specified time of operation. Service availability is based on the agreed service time and the downtime Service availability (%) = Agreed service time Downtime Agreed service time (Agreed service time is the period where the service is supposed to be available) 5

6 Causes of Cloud Service Unavailability Application failure For example, due to catastrophic exceptions caused by bad logic Data loss Infrastructure component failure Failure of dependent services Data center or site down Refreshing IT infrastructure 7

7 Impact of Cloud Service Unavailability Cost of unavailability of services is greater than ever - Outages could cost millions of dollars per hour Unavailability of service also affects reputation - Customers, financial markets, banks, and business partners Loss of revenue - Direct loss, compensatory payments, future revenue loss, and investment loss 8

8 Methods to Achieve Required Cloud Service Availability Building resilient cloud infrastructure facilitates meeting the required service availability Building resilient cloud infrastructure requires various high availability solutions Implementing fault tolerance mechanisms Deploying redundancy at both cloud infrastructure component level and site level to avoid single point of failure Deploying data protection solutions such as backup and replication Implementing automated cloud service failover Architecting resilient cloud applications 9

9 Lesson Summary During this lesson the following topics were covered: Business continuity Cloud service availability Causes of service unavailability Impact of cloud service unavailability Methods to achieve the required cloud service availability 10

10 Lesson: Building Fault Tolerance Cloud Infrastructure 1 This lesson covers the following topics: Avoiding single points of failure Key fault tolerance mechanisms 11

11 Single Points of Failure Single Points of Failure Refers to any individual component or aspect of an infrastructure whose failure can make the entire system or service unavailable. Single points of failure may occur at Component level (compute, storage, and network) Site or data center level 12

12 Avoiding Single Points of Failure Single points of failure can be avoided by implementing fault tolerance mechanisms such as redundancy Implement redundancy at component level Compute Storage Network Implement multiple service availability zones Avoids single points of failure at data center (site) level Enable service failover globally It is important to have high availability mechanisms that enable automated service failover 13

13 Implementing Redundancy at Component Level Key techniques to protect compute Clustering VM live migration Key techniques to protect network connectivity Link and switch aggregation NIC teaming Multipathing In-service software upgrade Configuring redundant hot swappable components Key techniques to protect storage RAID and erasure coding Dynamic disk sparing Configuring redundant storage system components 14

14 Compute Clustering Compute Clustering A technique where at least two compute systems (or nodes) work together and are viewed as a single compute system to provide high availability and load balancing. Enables service failover in the event of compute system failure to another system to minimize or avoid any service outage Two common clustering implementations are: Active/active Active/passive Hypervisor cluster is a common clustering implementation in cloud environment 15

15 Hypervisor Cluster Multiple hypervisors running on different systems are clustered Provides continuous availability of services running on VMs even if a physical compute system or a hypervisor fails Typically a live instance (i.e., a secondary VM) of a primary VM is created on another compute system 16

16 Virtual Machine Live Migration Running services on VMs are moved from one physical compute system to another without any downtime Allows scheduled maintenance without any downtime Facilitates VM load balancing 17

17 Link and Switch Aggregation Link aggregation Combines links between two switches and also between a switch and a node Enables network traffic failover in the event of a link failure in the aggregation Enables distribution of network traffic across links in the aggregation Switch aggregation Provides fault tolerance against switch and link failures Improves node performance by providing more active paths and bandwidth 18

18 NIC Teaming NIC Teaming A link aggregation technique that groups NICs so that they appear as a single, logical NIC to the OS or hypervisor. Provides network traffic failover in the event of a NIC/link failure Distributes network traffic across NICs NICs within a team can be configured as active and standby 19

19 Multipathing Enables a compute system to use multiple paths for transferring data to a LUN Enables failover by redirecting I/O from a failed path to another active path Performs load balancing by distributing I/O across active paths Standby paths become active if one or more active paths fail 20

20 In-Service Software Upgrade (ISSU) Allows updating software on network devices (switches and routers) without impacting the network availability Eliminates the need to stop the ongoing process on a device Ensures network availability as a result of a network device maintenance or upgrade processes Typically requires a network device with redundant control plane elements (supervisor or routing engines) This setup allows the administrator to update the software image on one engine while the other maintains network availability 21

21 RAID and Dynamic Disk Sparing RAID Combines multiple drives into a logical unit called a RAID set Provides data protection against drive failure Dynamic disk sparing Automatically replaces a failed drive with a spare drive to protect against data loss Multiple spare drives can be configured to improve availability A1 B1 C P A2 B P C Q A P B Q RAID 6 -Dual Distributed Parity A Q B2 C1 C2 22

22 Erasure Coding Provides space-optimal data redundancy to protect data loss against multiple drive failure A set of n disks is divided into m disks to hold data and k disks to hold coding information Coding information is calculated from data 23

23 Storage Resiliency Using Mirrored LUN Mirrored LUN is created using virtualization appliance Each I/O to the LUN is mirrored to the LUNs on the storage systems Mirrored LUN is continuously available to the compute system Even if one of the storage systems is unavailable due to failure 24

24 Lesson Summary During this lesson the following topics were covered: Single points of failure Clustering and VM live migration Aggregation and multipathing In-service software upgrade RAID, erasure coding, and dynamic drive sparing Storage resiliency using mirrored LUN 25

25 Lesson: Building Fault Tolerance Cloud Infrastructure 2 This lesson covers the following topics: Service availability zone Automated service failover across zones Active/passive and active/active zone configurations Live migrations across zones using stretched cluster 26

26 Service Availability Zones A service availability zone is a location with its own set of resources and isolated from other zones A zone can be a part of a data center or may even be comprised of the whole data center Enables running multiple service instances within and across zones to survive data center or site failure In the event of outage, the service should seamlessly failover across the zones Zones within a particular region are typically connected through low-latency network Enables faster cloud service failover 27

27 Automated Service Failover Across Zones Automated service failover Ensures robust and consistent failover Enables to meet stringent service levels Reduces RTO Automated failover process primarily depends on: Replication across zones Live migration with stretched cluster (zones in different remote locations) Reliable network infrastructure between zones Zones can be configured as active/passive and active/active configuration 28

28 Active/Passive Zone Configuration 29

29 Active/Active Zone Configuration 30

30 VM Migration Across Zones Using Stretched Cluster 31

31 Lesson Summary During this lesson the following topics were covered: Service availability zones Active/passive and active/active zone configurations VM migration across zones using stretched cluster 33

32 Lesson: Data Protection Solution Backup This lesson covers the following topics: Backup and recovery Backup requirements in a cloud environment Guest-level and image-level backup method Backup as a Service Backup service deployment options Deduplication for backup environment 34

33 Data Protection Overview Protecting critical data ensures availability of services Seamless service failover requires the availability of data Businesses also implement data protection solutions in order to comply with regulatory requirements Individual services and associated data sets have different business values, require different data protection strategies Two common data protection solutions: Backup Replication 35

34 Introduction to Backup and Recovery Backup An additional copy of production data, created and retained for the sole purpose of recovering lost or corrupted data. RPO and RTO are the primary considerations in selecting and implementing a specific backup strategy RPO specifies the time interval between two backups RTO relates to the time taken to recover data from backup RTO influences the type of backup target that should be used To implement a successful backup and recovery solution Service providers need to evaluate the backup methods along with their recovery considerations and retention requirements 36

35 Backup Requirements in a Cloud Environment Backup requires integration between backup application and management server of virtualized environment Backup requirements may differ from one service to another based on RTO and RPO Requires well-defined backup strategies to meet the requirements Recovery requires file level and/or full VM recovery Huge volume of redundant data in the backup environment Large number of VMs having identical data and configurations Backup and recovery operations need to be automated 37

36 Key Backup Components Backup client Gathers the data that is to be backed up Sends the data to the storage node Backup server Manages backup operations Maintains backup catalog Storage node Responsible for writing data to backup device Backup device (backup target) Tape library, disk library, and virtual tape library 38

37 Backup Targets Backup Targets Description Tape Library Tapes are portable and can be used for long term offsite storage Must be stored in locations with a controlled environment Not optimized to recognize duplicate content Data integrity and recoverability are major issues with tape-based backup media Disk Library Enhanced backup and recovery performance Disks also offer faster recovery when compared to tapes No inherent off-site capability, and is dependent on additional technologies such as replication to comply with off-site requirements Disk-based backup appliance includes features such as deduplication, compression, encryption, and replication to support business objectives Virtual Tape Library Disks are emulated and presented as tapes to backup software Does not require any additional modules or changes in the legacy backup software Provides better performance and reliability over physical tape Does not require the usual maintenance tasks associated with a physical tape drive, such as periodic cleaning and drive calibration 39

38 Backup Methods Two key backup methods: Guest-level Image-level 40

39 Guest-level Backup Backup agent is installed on each VM Performs file-level backup and recovery Does not backup VM configuration files Performing backup on multiple VMs on a compute system may consume more resources and lead to resource contention Impacts performance of applications running on VMs A A A = Backup Agent Application Servers Backup Server/ Storage Node Backup Device 41

40 Image-level Backup Creates a copy of the entire virtual disk and configuration data associated with a particular VM Backup is saved as a single entity called a VM image Provides VM image-level and file-level recovery No backup agent is required inside the VM to backup Backup processing is offloaded from VMs to a proxy server A Proxy Server Create Snapshot Mount the Snapshot Backup VM Snapshot Application Servers FS Volume Backup Device 42

41 Backup as a Service Enables consumers to procure backup services on demand Provides offsite backup for consumer desktops, laptops, and application servers Backs up data to the cloud storage Reduces the backup management overhead Transformation from CAPEX to OPEX Pay-per-use/subscription-based pricing Gives consumers the flexibility to select a backup technology based on their current requirements 43

42 Backup Service Deployment Options Managed Backup Service - Suitable when a cloud service provider already hosts consumer applications and data - Backup service is offered by the provider to protect consumer s data - Backup is managed by the service provider Replicated Backup Service - Service provider only manages data replication and IT infrastructure at disaster recovery site - Local backups are managed by consumers Remote Backup Service - Service provider receives data from consumers - Backup is managed by the service provider 44

43 Drivers for Optimizing Backup 45

44 Introduction to Data Deduplication Data Deduplication The process of detecting and identifying the unique data segments within a given set of data to eliminate redundancy. Deduplication process Chunk the data set Identify duplicate chunk Eliminate the redundant chunk Deduplication After Deduplication Unique segments = 3 Before Deduplication Total segments = 39 46

45 Deduplication Granularity Level File-level deduplication Detects and removes redundant copies of identical files Only one copy of the file is stored; the subsequent copies are replaced with a pointer to the original file Does not address the problem of duplicate content inside the files Sub-file level deduplication Breaks files down to smaller segments Detects redundant data within and across files Two methods: Fixed-length block Variable-length block 47

46 Deduplication Method Source-based deduplication Eliminates redundant data at the source (backup client) Client sends only new, unique segments across the network Reduces storage and network bandwidth requirements Increases overhead on the backup client Target-based deduplication Offloads deduplication process from the backup client Data is deduplicated at the target either inline or post-process 48

47 Lesson Summary During this lesson the following topics were covered: Backup requirements in a cloud environment Guest-level and image-level backup methods Backup as a Service Backup service deployment options Source-based and target-based deduplication 50

48 Lesson: Data Protection Solution-Replication This lesson covers the following topics: Replication and its types Snapshot and mirroring Synchronous and asynchronous remote replication Continuous Data Protection (CDP) Disaster Recovery as a Service (DRaaS) 51

49 Introduction to Replication Replication Process of creating an exact copy (replica) of the data for ensuring availability of services. Replica copies are used to restore and restart services if data loss occurs Based on the SLA for the service being offered to the consumers, data can be replicated to one or more locations Replication can be classified Local replication Snapshot and mirroring Remote replication Synchronous and asynchronous 52

50 Local Replication: Snapshot A virtual copy of a set of files, or volume as they appeared in a particular PIT Provides the ability to restore the files or volumes if there is a data loss or corruption Virtual machine snapshot is a common snapshot technique, that preserves the state and data of a VM at a specific PIT When a snapshot is created, a child virtual disk (delta disk file) is created from the base image or parent virtual disk Successive snapshots generate a new child virtual disk from the previous child virtual disk Snapshots hold only changed blocks 53

51 Local Replication: Mirroring 54

52 Remote Replication: Synchronous Write is committed to both the source and the remote replica before it is acknowledged to the compute system Ensures that the source and the replica have identical data at all times Provides near zero RPO Compute System Compute system writes data to source. 2. Data from source is replicated to replica (target). 3. Target acknowledges back to source. 4. Source acknowledges write complete to the compute system. Storage (Source) Primary Zone (Source site) 2 3 Secondary Zone (Remote Site) Storage (Replica) 55

53 Remote Replication: Asynchronous A write is committed to the source and immediately acknowledged to the compute system Data is buffered at the source and transmitted to the remote site later Replica will be behind the source by a finite amount (finite RPO) Compute System Compute system writes data to source. 2. Write is immediately acknowledged to compute system. 3. Data is transmitted to the replica (target). 4. Target acknowledges back to source. Storage (Source) 3 4 Storage (Replica) Primary Zone (Source Site) Secondary Zone (Remote Site) 56

54 Advanced Replication Solution: CDP Provides the ability to restore data to any previous PIT Enables to meet the required recovery level for an application Data changes are continuously captured and stored in a separate location from the production data Supports both local and remote replication To meet operational and disaster recovery respectively 57

55 Key CDP Components Journal volume Contains all the data that has changed from the time the replication session started to the production volume Journal size determines how far back in time the recovery points can go CDP appliance Intelligent hardware platform that runs the CDP software Manages both the local and the remote replications Write splitter Intercept writes to the production volume from the compute system and splits each write into two copies Can be implemented at the compute, fabric, or storage system 58

56 CDP Operations: Local and Remote Replication 59

57 Replication Use Case: DRaaS Service provider offers resources to enable consumers to run their IT services in the event of a disaster Resources at the service provider location can be dedicated to the consumer or they can be shared Replication is a key technique used by the service provider in order to offer DRaaS to the consumers Service provider should design, implement, and document a DRaaS solution specific to the customer s infrastructure 60

58 DRaaS Normal Production Operation IT services run at the consumer s production data center Replication occurs from the consumer production environment to the service provider s data center over the network Data is usually encrypted while replicating to the provider s location VM instances are not allocated Network Storage Compute Systems Consumer Production Data Center Storage Replication Cloud Service Provider 61

59 DRaaS Business Disruption Business operations failover to the provider s infrastructure in the event of a disaster at consumer s data center Users at the consumer organization are redirected to the cloud Typically VM instances are created from a pool of compute Connect replicated storage to each of the newly activated VMs Disaster VM instances are invoked to run the service Network Compute Systems Storage Consumer Production Data Center Cloud Service Provider 62

60 Lesson Summary During this lesson the following topics were covered: Snapshot and mirroring Synchronous and asynchronous remote replication Continuous Data Protection Disaster Recovery as a Service 63

61 Lesson: Application Resiliency for Cloud This lesson covers the following topics: Resilient cloud application Key design strategies for application resiliency Monitoring applications for availability 64

62 Resilient Cloud Applications Overview Cloud applications have to be designed to deal with IT resources failure to guarantee the required availability Fault resilient applications have logic to detect and handle transient fault conditions to avoid application downtime Key application design strategies for improving availability Graceful degradation of application functionality Retry logic in application code Persistent application state model Event-driven processing 65

63 Graceful Degradation Application maintains the limited functionality even when some of the modules or supporting services are not available Unavailability of certain application components or modules should not bring down the entire application For example, an e-commerce site can continue to collect orders even if its payment gateway is unavailable Provides the ability to process orders when the payment gateway is once again available or after failing over to a secondary gateway 66

64 Fault Detection and Retry Logic Refers to a mechanism that implements a logic in the code of an application to improve the availability To detect and retry the service that is temporarily down May result in successful restore of service A retry strategy must be defined to state how many retries can be attempted before deciding the fault is not transient A successful retry attempt typically goes unnoticed to the application users 67

65 Persistent Application State Model and Eventdriven Processing Persistent application state model Application state information is stored out of the memory Stored in a data repository If an instance fails, the state information is still available in the repository Asynchronous event-driven processing Applications are written in a way to process the user request from a queue asynchronously instead of synchronous call Allows multiple applications instances to process requests If an instance is lost, the impact is minimal 68

66 Monitoring Application Availability Specialized tools provide the capability to monitor the availability of application instance that runs on VMs Minimizes downtime associated with the application failure Typically this tool is integrated with VM management software When there is an error or failure in an application The tool attempts to restart the application within the VM If the application does not restart successfully, the tool communicates to VM management software VM management software in turn automatically restart the VM 69

67 Lesson Summary During this lesson the following topics were covered: Graceful degradation of application functionality Retry logic in application code Persistent application state model Event-driven processing Monitoring application availability 70

68 Concepts in Practice EMC backup and deduplication products EMC replication products VMware BC solutions 71

69 EMC Backup and Deduplication Products NetWorker Avamar Data Domain/ ProtectPoint Software that centralizes, automates, and accelerates data backup and recovery Supports multiplexing Supports source-based, and target-based deduplication capabilities by integrating with EMC Avamar and EMC Data Domain, respectively Disk-based backup and recovery solution that provides inherent sourcebased deduplication Avamar provides a variety of options for backup, including guest OS-level backup and image-level backup Data Domain - Target-based data deduplication solution - Data Domain Boost software increases backup performance by distributing parts of deduplication process to backup server ProtectPoint - Backs up data directly from primary storage to Data Domain system 72

70 EMC Replication Products VNX Snapshot/SnapView TimeFinder/SRDF RecoverPoint/VPLEX VNX Snapshot - Creates a PIT copy of a source LUN SnapView - EMC VNX array-based local replication software - Creates pointer-based virtual copy and full-volume mirror of the source using SnapView Snapshot and Clone respectively TimeFinder - EMC VMAX array-based local replication software - Uses TimeFinder/Snap to create pointer-based virtual copy and TimeFinder/Clone for pointer-based full-volume replica SRDF - A family of remote replication solutions for EMC VMAX arrays - Includes SRDF/Synchronous, SRDF/Asynchronous, and SRDF/Star RecoverPoint - Solution for both local and remote CDP - Enables to access data for any previous PIT VPLEX - Enables mirroring data of a virtual volume both within and across locations - Uses a clustering architecture and data caching techniques 74

71 VMware BC Solutions vcenter Site Recovery Manager A VMware tool that makes disaster recovery rapid, reliable, and manageable Provides an interface for setting up recovery plans Automates both failover and failback process that ensures highly predictable RPO and RTO Integrates tightly with replication products, vsphere, and vcenter Server VMware FT Provides continuous availability for application in the event of server failure Creates a live shadow instance of a VM that is in virtual lockstep with the primary instance FT eliminates even the smallest chance of data loss or disruption VMware HA Provides high availability for applications running in virtual machines In the event of the physical compute system failure, affected VMs are automatically restarted on other compute systems 75

72 VMware BC Solutions (Cont'd) vmotion Enables live migration of running VMs from one physical server to another without any downtime Capable of migrating VMs running any OS across any type of hardware and storage supported by ESXi Storage vmotion Enables live migration of VM disk files within and across storage arrays with no downtime Enables to perform proactive storage migrations, improve VM storage performance and free up valuable storage capacity 76

73 Module Summary Key points covered in this module: Business continuity Cloud service availability Fault tolerance mechanisms for cloud infrastructure Backup and deduplication Local and remote replication Fault resilient cloud application design strategies 77