Linux ClusterAdministration

RHEL 5

1Linux Clustering Document www.linoxide.com

2Linux Clustering Document

Cluster BasicsWhat is cluster

Cluster typesStorageHigh AvailabilityLoad balancingHigh performance

Linux Cluster Concepts And Administration on RHEL 5

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3Linux Clustering Document

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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4Linux Clustering Document

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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5Linux Clustering Document

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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6Linux Clustering Document

Performance ClustersUse cluster nodes to perform concurrentcalculations

Allow applications to work in parallel

Referred to as computational clusters or gridcomputing

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7Linux Clustering Document

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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8Linux Clustering Document

Red Hat Cluster SuiteRHCS

Linux Cluster Concepts And Administration on RHEL 5

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9Linux Clustering Document

Cluster Management

Lock Management

Fencing

Cluster Configuration Management

Cluster Infrastructure

Linux Cluster Concepts And Administration on RHEL 5

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10Linux Clustering Document

Cluster Infrastructure Cluster Management(CMAN)

Distributed across all nodes

CMAN track cluster quorum Prevents split-brain

CMAN tracks membership

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11Linux Clustering Document

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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12Linux Clustering Document

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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13Linux Clustering Document

Fencing methods:

SCSI3 Persistent Reservation Fencing

Fiber Channel switch fencing

GNBD fencing

Cluster Infrastructure Fencing

Power fencingExternalIntegrated

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14Linux Clustering Document

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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15Linux Clustering Document

Configuration file /etc/cluster/cluster.conf

Cluster characteristics

Cluster Infrastructure Cluster ConfigurationSystem (CCS)

Cluster nameClusterFence DeviceManaged Resources

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16Linux Clustering Document

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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17Linux Clustering Document

Failover Domains

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Failover DomainsFailover characteristics

UnrestrictedRestrictedUnorderedOrderedFailback

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19Linux Clustering Document

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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20Linux Clustering Document

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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21Linux Clustering Document

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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22Linux Clustering Document

Global Network BlockDevice (GNBD)

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23Linux Clustering Document

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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24Linux Clustering Document

Linux Virtual Server (LVS)

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25Linux Clustering Document

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 Virtual Server (LVS)

Load-balancing algorithms:

Round-Robin SchedulingWeighted Round-Robin SchedulingLeast-ConnectionWeighted Least-Connections (default)

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NAT RoutingDirect Routing

27Linux Clustering Document

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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29Linux Clustering Document

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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30Linux Clustering Document

System-config-cluster

Cluster status tool

Cluster Administration GUI

Linux Cluster Concepts And Administration on RHEL 5

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- ccs_tool → cluster configuration- cman_tool → cluster management- fence_tool → fence tool- clustat → cluster status- clusvcadm → cluster user service administration

31Linux Clustering Document

Command Line Administration Tools

Cluster Administration tools

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