Linux Cluster. Administration

Transcription

1 Administration RHEL 5 Linux Cluster 1

2 Cluster Basics What is cluster Cluster types Storage High Availability Load balancing High performance 2

3 Storage Clusters Provide consistent file system image across nodes Simplify storage administration Simplify backup & disaster recovery RHCS provides storage clustering through Red Hat GFS 3

4 High Availability Clusters Provide continuous availability of services Maintain data integrity Node failures in a high-availability cluster are not visible from outside the cluster RHCS provides high-availability clustering through its High availability Service Management component 4

5 Load balancing clusters Dispatch network service requests to multiple cluster nodes Provide cost-effective scalability Failures in a load-balancing cluster are not visible from outside the cluster RHCS provides load-balancing through LVS 5

6 Performance Clusters Use cluster nodes to perform concurrent calculations Allow applications to work in parallel Referred to as computational clusters or grid computing 6

7 Red Hat Cluster Suite RHCS RHCS major components: Cluster infrastructure HA Service Management Cluster Administration tools Linux Virtual Server ( LVS) RHCS optional components Global File System (GFS) Cluster Logical Volume Manager (CLVM) Global Network Block Device (GNBD) 7

8 Red Hat Cluster Suite RHCS 8

9 Cluster Infrastructure Cluster Management Lock Management Fencing Cluster Configuration Management 9

10 Cluster Infrastructure Cluster Management (CMAN) Distributed across all nodes CMAN track cluster quorum Prevents split-brain CMAN tracks membership 10

11 Cluster Infrastructure Lock Management Service provides mechanism for other cluster components to synchronize their access to shared resources Distributed Lock Manager (DLM) GFS & CLVM use locks from DLM 11

12 Cluster Infrastructure Fencing Disconnection of a node from the cluster s shared storage fenced daemon performs fencing DLM & GFS recover after fenced Fencing methods 12

13 Cluster Infrastructure Fencing Fencing methods: Power fencing External Integrated SCSI3 Persistent Reservation Fencing Fiber Channel switch fencing GNBD fencing 13

14 Cluster Infrastructure Cluster ConfigurationSystem (CCS) CCS manage cluster configuration CCS provide information to other cluster components CCS ensures configuration file is up-to-date in all nodes 14

15 Cluster Infrastructure Cluster ConfigurationSystem (CCS) Configuration file /etc/cluster/cluster.conf Cluster characteristics Cluster name Cluster Fence Device Managed Resources 15

16 HA Service Management Create & 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 16

17 Failover Domains 17

18 Failover Domains Failover characteristics Unrestricted Restricted Unordered Ordered Failback 18

19 Red Hat Global File System 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) 19

20 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 extensions to LVM2 20

21 Global Network Block Device (GNBD) Provides block-device access to GFS over TCP/IP Useful when FC or single initiator SCSI are not necessary or are cost prohibitive GNBD client, GNBD server 21

22 Global Network Block Device (GNBD) 22

23 Linux Virtual Server (LVS) Set of integrated s/w for load balancing Runs on equally configured computers Active LVS router Backup LVS router LVS roles: Load balancing Integrity of services check 23

24 Linux Virtual Server (LVS) 24

25 Linux Virtual Server (LVS) Two tiers : LVS routers & real servers Active LVS router uses NAT to direct from public 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 load balancing algorithms 25

26 Linux Virtual Server (LVS) Load-balancing algorithms: Round-Robin Scheduling Weighted Round-Robin Scheduling Least-Connection Weighted Least-Connections (default) 26

27 Linux Virtual Server (LVS) Routing Methods: NAT Routing Direct Routing 27

28 Cluster Administration tools Conga Cluster Administration GUI Command line administration tools 28

29 Cluster Administration tools Conga s/w provides centralized configuration & management Conga primary components luci ricci luci server runs on one computer & communicates with multiple clusters & computers via ricci ricci agent that runs on each computer 29

30 Cluster Administration GUI System-config-cluster Cluster status tool 30

31 Cluster Administration tools Command Line Administration Tools - ccs_tool cluster configuration - cman_tool cluster management - fence_tool fence tool - clustat cluster status - clusvcadm cluster user service administration 31