Designing High Availability and Business Continuity
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Learning Objectives • Understand the differences between Network Load Balancing (NLB) clusters and failover clusters • Design an NLB cluster • Design a failover cluster • Understand methods used to back up and restore Active Directory
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Load Balancing and Fault Tolerance • Ensures service available to users when needed • Load balancing at the server level – Achieved using load-balancing clusters
• Fault tolerance at the server level – Achieved using failover clusters
• Failover clusters – Primary method of achieving high server level availability
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Load Balancing and Fault Tolerance (cont’d.) • Load-balancing clusters – Two or more servers configured together – Load balanced between the servers
• Failover clusters – Two or more servers configured together • Some servers designated as active nodes • Some servers designated as inactive nodes
• Goals of load balancing and failover clusters – Scalability and high availability MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Scalability • Service’s ability to support more clients – Add resources • Processing power or more servers
• Achieved by scaling up – Adding additional resources to a server
• Achieved by scaling out – Adding additional servers
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-1 Scaling up by increasing hardware resources in a server Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-2 Scaling out by increasing the number of servers Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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High Availability • Service available when needed • Different levels – 99 percent uptime: misleading – One percent downtime equates to: • More than 87 hours of downtime in a year
• High level of uptime – Referred to as “five nines” or 99.999 percent uptime
• Failover clusters – Used to achieve high availability MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Table 8-1 Server availability percentages and times
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Network Load Balancing vs. Failover Clusters
Table 8-2 A comparison of NLB and failover clusters MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Network Load Balancing vs. Failover Clusters (cont’d.) • Comprehensive solution – Combines NLB cluster and failover cluster – Cannot use both services on the same server – Within a network • Can use both services for different layers of support
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-3 Using an NLB cluster and a failover cluster in a single solution Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Network Load Balancing • Network Load Balancing (NLB) – – – –
Windows Server 2008 feature Increases stability Provides application and service scalability Recommended for Internet-facing or Internetaccessible servers • Internet Information Services (IIS) Web servers • File Transfer Protocol (FTP) servers • Firewalls, proxy servers, VPN servers
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Network Load Balancing (cont’d.) • Stateless servers – Configured to operate independently of other cluster servers
• NLB cluster – Monitors cluster hosts – Dynamically adds and removes hosts – Hosts exchange heartbeat messages with other cluster members
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-4 NLB cluster Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Network Load Balancing Manager • Primary tool to create and configure NLB clusters • Host fails – Status changes to Unreachable – Clients no longer directed to the failed host
• Failed host brought back online – Status changes Pending when it begins – Status changes to Converged once added
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-5 Cluster created in Network Load Balancing Manager Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Adding Network Load Balancing • All hosts within an NLB cluster – Must have the NLB feature installed
• Use Server Manager to add feature • Activity 8-1: Adding the Network Load Balancing Feature
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Creating an NLB Cluster • Performed after adding NLB feature to hosts • Network Load Balancing Manager – Used by any host to create or manage cluster
• Creating an NLB cluster – Identify parameters for cluster and hosts in the cluster – Can create or modify IP traffic rules
• Cluster operation mode – Indicates if cluster using unicast, multicast, or Internet Group Multicast (IGMP) – Unicast • Most common mode used (recommended) MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-6 Cluster parameters for a new cluster Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Creating an NLB Cluster (cont’d.) • Port rules identify traffic balanced by NLB cluster – Default: • All IP traffic load balanced and identified with a filter
• Filter includes: – All cluster IP addresses and all TCP and UDP ports
• Possible to create cluster balancing specific traffic – Examples: • TCP port 80 for HTTP traffic • TCP port 443 for HTTPS traffic
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-7 Host parameters within a cluster Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Creating an NLB Cluster (cont’d.) • Activity 8-2: Creating a Network Load Balancing Cluster
Figure 8-8 Connecting to DC1 as the first host in a cluster Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-9 NLB cluster created Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Adding Hosts to an NLB Cluster • Accomplished after creating NLB cluster • Steps – Add the feature to the server – Use the Network Load Balancing Manager to add the host
• Any server with Network Load Balancing Manager installed can have a host • Activity 8-3: Adding a Host to an NLB Cluster
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-10 Verifying parameters of second host in NLB cluster Courtesy Course Technology/Cengage Learning MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Removing the NLB Cluster Service • Does not require much effort • Remove NLB cluster feature if not being used – Can interfere with other components and services
• Activity 8-4: Removing the NLB Cluster and the NLB Cluster Feature
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Failover Clusters • Group of independent servers – Configured together • Provide high availability of a service or application
• Servers within a failover cluster – Referred to as nodes
• If one node fails: – Another node able to take over the load
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-11 A two-node failover cluster Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Failover Clusters (cont’d.) • Windows Server 2008 Enterprise and Datacenter editions – Support as many as 16 nodes in a failover cluster
• Possible to host different services and applications on different nodes – Can quickly become complex • Reduces reliability of the failover cluster
• Most enterprises – Use a single two-node failover cluster • For specific service or application MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Failover Clusters (cont’d.) • Key terms – Failover – Failback
• Nodes in the cluster have access to shared storage – Other systems • Do not have direct access to the storage
• Storage – Serial attached SCSI (SAS) array – Storage area network (SAN) MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Failover Cluster Requirements • More stringent than requirements supporting NLB cluster • Hardware purchased specifically to support the failover cluster – Often higher cost
• Operating system – Server must be running the Windows Server 2008 Enterprise, Datacenter, or Itanium Edition
• Application – Application or services must be cluster aware MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Failover Cluster Requirements (cont’d.) • Hardware – Closely matched – Marked as “Certified for Windows Server 2008”
• Shared storage – Available to all cluster nodes – Often includes internal redundancy • RAID-5 or RAID-10
• Network adapters – At least one network adapter connects nodes
• Validate a Configuration wizard validates hardware MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Quorums • Quorum model – Changed in Windows Server 2008 • Combines nodes and shared disk resources to create a quorum
• Each node and shared resource – Has a vote in the quorum
• Quorum established in different ways
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Quorums (cont’d.) • Quorum (generally) – Refers to minimum number of members required to conduct business and make decisions
• Failover cluster requirement – Majority of votes • To continue operating the cluster after failure
• Four quorum models available – From the Failover Cluster Management console
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-12 Selecting a quorum model Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Quorums (cont’d.) • Available quorum models – No Majority (Disk Only) • Same as the Windows Server 2003 shared disk quorum • If the disk fails, the cluster fails
– Node Majority • Same as Windows 2003 majority node set • Does not include the disk in the quorum
– Node and Disk Majority • Nodes and disks allowed to vote in the quorum MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Quorums (cont’d.) • Available quorum models (cont’d.) – Node and File Share Majority • Similar to Node and Disk Majority • Exception: shared resource not actually a disk • Resource: share accessible by cluster nodes
• Quorum model choice – Dependent on number of nodes in the cluster
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-13 A two-node failover cluster with a witness Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Table 8-3 Quorum model recommendations
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Cluster Storage and Storage Solutions • Failover clusters require dedicated storage • Must understand: – Windows Server 2008 failover clusters storage types – Storage solutions hosting the disks
• Storage formatting – Format as basic disks with NTFS – Windows Server 2008 failover clusters • Do not provide native support for dynamic disks
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Cluster Storage and Storage Solutions (cont’d.) • Windows Server 2008 failover cluster disk storage formats – Master boot record (MBR) – GUID Partition Table (GPT)
• Failover cluster disks – Hosted in a dedicated storage solution • Includes built-in redundancy for each disk • Uses Redundant Array of Inexpensive Disks (RAID) • Example: RAID-5 or RAID-10
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Cluster Storage and Storage Solutions (cont’d.) • Directly attached Small Computer System Interface (SCSI) disks – Supported with previous versions of clustering – Not supported with Windows Server 2008 clustering
• Common storage solutions supported – Serial attached SCSI (SAS) array – Storage area network (SAN)
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Logical Unit Numbers in Storage Arrays • Logical unit numbers (LUNs) – Identify storage volumes within storage arrays
• Using LUNs with failover clusters – Must be isolated from other servers
• Storage solutions – Used for much more than just failover clusters – Will not have a separate storage array • Dedicated to the failover cluster
– Must ensure separate LUNs dedicated for the cluster MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-14 Assigning LUNs to failover clusters Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Logical Unit Numbers in Storage Arrays (cont’d.) • Multiple LUNs assigned to any cluster – Dependent on applications and services needs
• Microsoft’s Hyper-V virtualization technology – Hosts several servers – Allows multiple physical server consolidation • Single host server in a virtual environment
– Drawback: host server becomes single point of failure – Solution: add second identical server • Virtual servers configured in three separate failover clusters MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-15 Assigning LUNs with Hyper-V Courtesy Course Technology/Cengage Learning MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Cluster Connectivity to Storage Solutions • Significant concern – Connectivity to storage disks
• Connectivity method – Affects cost, performance, fault tolerance
• Two primary supported connectivity types: – Fibre Channel • Uses twisted-pair or fiber-optic media • Commonly uses fiber today
– iSCSI • Uses TCP/IP to transfer data MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Table 8-4 A comparison of Fibre Channel and iSCSI connectivity
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Cluster-Aware Services and Applications • Designed to work with failover cluster components • Communicates status to cluster – Failover cluster knows: • When service or application failed • When cluster needs to fail over to another node
• Generic applications, scripts, services – Can work within a failover cluster • Cluster not as reliable if failure occurs
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-16 Selecting a service or application for a failover cluster Courtesy Course Technology/Cengage Learning MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Cluster-Aware Services and Applications (cont’d.) • Common services and applications used with failover clusters – – – –
Application servers DFS Namespace Server DHCP servers File and print servers
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Failover Clusters for Multiple Sites • Failover clusters may have nodes located in other sites • Benefits – Users connect to the local server for quick responses – Local server failure • Other site nodes respond to user requests
• Failover clusters in multi-site configurations – Used and configured differently
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-17 Multi-site failover cluster with a witness share Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Failover Clusters for Multiple Sites (cont’d.) • Node and File Share Majority quorum model in a two-node failover cluster – Allows witness share to vote – If either node fails: • Ensures continued operation
• Node and File Share Majority quorum model in a multi-site cluster configuration – Used with even number of nodes
• If three sites and three nodes in the multi-site cluster – Use Node Majority quorum model MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Adding the Failover Cluster Feature • Failover Cluster Management console – – – –
Validates node hardware configuration Creates and manages clusters Added as a feature in Windows Server 2008 Includes links for help and additional documentation on clusters
• Activity 8-5: Adding the Failover Clustering Feature
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-18 The Failover Cluster Management console Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Running the Validate a Configuration Wizard • • • •
Run after Failover Clustering feature added Validates hardware used in the failover cluster Validates cluster configuration Primary reason failover clusters do not work as expected – Hardware incompatibilities
• Activity 8-6: Validating Hardware
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-19 Viewing the result of the Validate a Configuration wizard Courtesy Course Technology/Cengage Learning MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Creating a Failover Cluster • Failover Cluster Management console – Used to add a failover cluster
• Activity 8-7: Creating a Failover Cluster
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-20 Using the Failover Cluster Management console to view the details of a node in a cluster Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-21 Viewing the result of the Validate a Configuration wizard Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Pausing, Stopping, and Removing Nodes in a Cluster • Example: – Need to perform maintenance on a node
• Results of pausing, stopping, evicting a node – Pause • Existing users and resources stay online • Users or resources cannot be added
– Stop • Stops the cluster service on the cluster node
– Evict • Used when the node no longer needed in the cluster MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-22 Evicting a node from a failover cluster Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Removing a Failover Cluster • Failover cluster no longer needed – Remove it by destroying it • Use the Failover Cluster Management console
• Failover Clustering feature – Can interfere with other server functions
• Activity 8-8: Destroying a Failover Cluster and Removing the Failover Clustering Feature
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-23 Destroying the failover cluster Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Active Directory Backup and Restores • Windows Server 2008 feature – Backs up and restores Active Directory – Includes several tools and wizards • Performs a single backup or schedule regular backups
• Two methods to back up Active Directory – Critical Volume backup – System State backup
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Adding the Windows Server Backup Feature • Windows Server Backup feature – Not installed by default
• Enterprises use more sophisticated third-party tools – Easier to back up and restore Active Directory
• Windows Server Backup feature not always needed • Two Windows Server Backup features can be added – Windows Server Backup – Command-line tools MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Adding the Windows Server Backup Feature (cont’d.) • Windows Server Backup – Must be included when Windows Server Backup feature added
• If automating backups using Windows PowerShell: – Must add command-line tools
• Can automate backups using: – Wbadmin commands in batch files – Schedule feature within Windows Server Backup GUI
• Activity 8-9: Adding the Windows Server Backup Feature MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Figure 8-24 Adding the Backup feature Courtesy Course Technology/Cengage Learning MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Backing Up Active Directory • Performed after Windows Server Backup feature installed • Tools – Windows Server Backup graphical user interface (GUI) – Wbadmin command-line tool
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Backing Up Active Directory (cont’d.) • Limitations with native backup tools: – Cannot back up data from a critical volume • To same critical volume
– Cannot back up only system state data • Using Windows Server Backup console
– Cannot back up data to a network drive • Using Wbadmin command
• Backing up only system state data – Use the Wbadmin command-line tool • Wbadmin start systemstatebackup -backuptarget:x: MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Backing Up Active Directory (cont’d.) • Activity 8-10: Backing up a Critical Volume
Figure 8-25 Designating the target location for the backup Courtesy Course Technology/Cengage Learning
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Restoring Active Directory • Active Directory restore types – Non-authoritative restore – Authoritative restore
• Review replication between domain controllers • Steps to perform non-authoritative restore – Reboot server in Directory Services Restore Mode (DSRM) – Log on to DSRM using the DSRM account – Restore Active Directory – After restore completes • Reboot server MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Performing an Authoritative Restore • Follow non-authoritative restore steps • After restoring Active Directory and before rebooting server: – Use NTDSUtil command: • Restore deleted objects authoritatively • Update the USNs
– NTDSUtil shell command-line tool • Includes authoritative restore commands
– After objects marked for authoritative restore: • Reboot server normally MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Performing an Authoritative Restore (cont’d.) • Domain controller replicates with other domain controllers – Objects marked with NTDSUtil: • Considered the authority • Replicated to other domain controllers
• Performing authoritative restore with NTDSUtil – Use the object distinguished name (DN)
• Example DN: – Uniquely identifying user account named Darril in the Mgrs OU of the Wiley.com domain • CN=Darril, OU=Mgrs, DC=Wiley, DC=com MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Performing an Authoritative Restore (cont’d.) • DN components – Common name (CN) – Organizational Unit (OU) – Domain component (DC)
• Command prompt commands to authoritatively restore the Darril user account – – – –
Ntdsutil Activate Instance ntds Authoritative restore Restore Object “CN=Darril, OU=Mgrs, DC=Wiley, DC=com”
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Summary • Network Load Balancing (NLB) cluster – Includes two or more servers configured together – Increases scalability
• Scalability – Ability of a service or application to support additional clients at the same level of service • Add more resources
• High availability – Ensures service or application available when needed
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Summary (cont’d.) • Failover cluster – – – – –
Two or more servers configured together Provides high availability for a service or application More expensive than NLB clusters Uses a quorum Use either a serial attached SCSI (SAS) array or a storage area network (SAN)
• Connectivity to shared storage – Through Fibre Channel or iSCSI
MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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Summary (cont’d.) • Multi-site failover clusters – Reduce bandwidth usage over a WAN link – Provide fault tolerance if a server fails
• Failover support – Managed by the Failover Cluster Management console
• Windows Backup feature – Includes tools to back up and restore AD
• Active Directory restore – Non-authoritatively or authoritatively MCITP Guide to Microsoft Windows Server 2008 Enterprise Administration (Exam #70-647)
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