Linux Cluster Concepts
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Transcript of Linux Cluster Concepts
Linux ClusterAdministration
RHEL 5
1Linux Clustering Document www.expertslogin.com
2Linux Clustering Document www.expertslogin.com
Linux Cluster Concepts And Administration on RHEL 5
Cluster BasicsWhat is cluster
Cluster typesStorageHigh AvailabilityLoad balancingHigh performance
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Linux Cluster Concepts And Administration on RHEL 5
Storage ClustersProvide consistent file system image across nodes
Simplify storage administration
Simplify backup & disaster recovery
RHCS provides storage clustering through Red Hat GFS
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Linux Cluster Concepts And Administration on RHEL 5
High Availability ClustersProvide continuous availability of services
Maintain data integrity
Node failures in a high-availability cluster are not vis-ible from outside the cluster
RHCS provides high-availability clusteringthrough its High availability ServiceManagement component
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Linux Cluster Concepts And Administration on RHEL 5
Load balancing clustersDispatch network service requests to multiple cluster nodes
Provide cost-effective scalability
Failures in a load-balancing cluster are notvisible from outside the cluster
RHCS provides load-balancing through LVS
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Linux Cluster Concepts And Administration on RHEL 5
Performance ClustersUse cluster nodes to perform concurrentcalculations
Allow applications to work in parallel
Referred to as computational clusters or gridcomputing
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Linux Cluster Concepts And Administration on RHEL 5
Red Hat Cluster SuiteRHCS
RHCS major components:
RHCS optional components
Cluster infrastructureHA Service ManagementCluster Administration toolsLinux Virtual Server ( LVS)
Global File System (GFS)Cluster Logical Volume Manager (CLVM)Global Network Block Device (GNBD)
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Linux Cluster Concepts And Administration on RHEL 5
Red Hat Cluster SuiteRHCS
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Linux Cluster Concepts And Administration on RHEL 5
Cluster Management
Lock Management
Fencing
Cluster Configuration Management
Cluster Infrastructure
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Linux Cluster Concepts And Administration on RHEL 5
Cluster Infrastructure Cluster Management(CMAN)
Distributed across all nodes
CMAN track cluster quorum Prevents split-brain
CMAN tracks membership
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Linux Cluster Concepts And Administration on RHEL 5
Service provides mechanism for other cluster components to synchronize their access to shared resources
Distributed Lock Manager (DLM)
GFS & CLVM use locks from DLM
Cluster Infrastructure Cluster Management(CMAN)
Cluster InfrastructureLock Management
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Linux Cluster Concepts And Administration on RHEL 5
Cluster Infrastructure Fencing
Disconnection of a node from the cluster’s shared storage fenced daemon performs fencing
DLM & GFS recover after fenced
Fencing methods
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Linux Cluster Concepts And Administration on RHEL 5
Fencing methods:
SCSI3 Persistent Reservation Fencing
Fiber Channel switch fencing
GNBD fencing
Cluster Infrastructure Fencing
Power fencingExternalIntegrated
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Linux Cluster Concepts And Administration on RHEL 5
Cluster Infrastructure Cluster ConfigurationSystem (CCS)
CCS manage cluster configuration
CCS provide information to other clustercomponents
CCS ensures configuration file is up-to-datein all nodes
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Linux Cluster Concepts And Administration on RHEL 5
Configuration file /etc/cluster/cluster.conf
Cluster characteristics
Cluster Infrastructure Cluster ConfigurationSystem (CCS)
Cluster nameClusterFence DeviceManaged Resources
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Linux Cluster Concepts And Administration on RHEL 5
HA Service ManagementCreate & manage HA cluster services
rgmanager implements cold failover
HA service must be configured in cluster.conf
Associate service to failover domain
Failover priority in a failover domain
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Linux Cluster Concepts And Administration on RHEL 5
Failover Domains
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Linux Cluster Concepts And Administration on RHEL 5
Failover DomainsFailover characteristics
UnrestrictedRestrictedUnorderedOrderedFailback
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GFS/GFS2 is a native file system
GFS/GFS2 provides data sharing among nodes with single, consistent view of the file system name space
GFS/GFS2 file system must be created on an LVM logical volume (linear or mirror)
Red Hat Global File System
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Linux Cluster Concepts And Administration on RHEL 5
Cluster Logical Volume(CLVM)
CLVM provides the same capabilities as LVM2 on a single node
CLVM makes volume available to all nodes
clvmd daemon provides clustering exten-sionsto LVM2
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Provides block-device access to GFS overTCP/IP Useful when FC or single initiator SCSI are not necessary or are cost prohibitive
GNBD client , GNBD server
Global Network Block Device (GNBD)
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Global Network BlockDevice (GNBD)
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Linux Cluster Concepts And Administration on RHEL 5
Set of integrated s/w for load balancing
Runs on equally configured computers
LVS roles:
Linux Virtual Server (LVS)
Active LVS routerBackup LVS router
Load balancingIntegrity of services check
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Linux Cluster Concepts And Administration on RHEL 5
Linux Virtual Server (LVS)
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Linux Cluster Concepts And Administration on RHEL 5
Two tiers : LVS routers & real servers
Active LVS router uses NAT to direct frompublic network to real servers
Service requests arrive to LVS to a virtual IP (VIP)
Only one LVS is active at a time
LVS distributes requests based on loadbalancing algorithms
Linux Virtual Server (LVS)
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Linux Cluster Concepts And Administration on RHEL 5
Linux Virtual Server (LVS)
Load-balancing algorithms:
Round-Robin SchedulingWeighted Round-Robin SchedulingLeast-ConnectionWeighted Least-Connections (default)
NAT RoutingDirect Routing
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Routing Methods:
Linux Virtual Server (LVS)
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Cluster Administration tools
Conga
Cluster Administration GUI
Command line administration tools
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s/w provides centralized configuration &management
Conga primary components
luci server runs on one computer & commu-nicates with multiple clusters & computers via ricci
ricci agent that runs on each computer
Cluster Administration toolsConga
luciricci
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System-config-cluster
Cluster status tool
Cluster Administration GUI
- ccs_tool → cluster configuration- cman_tool → cluster management- fence_tool → fence tool- clustat → cluster status- clusvcadm → cluster user service administration
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Linux Cluster Concepts And Administration on RHEL 5
Command Line Administration Tools
Cluster Administration tools