Index

Symbols

/etc/hosts
editing, Editing the /etc/hosts File
/etc/sysconfig/ha/lvs.cf file, /etc/sysconfig/ha/lvs.cf
/etc/sysconfig/rawdevices
editing the file, Editing the rawdevices File

A

acknowledgments, Acknowledgments
active router
See LVS clustering
active-active configuration, Red Hat Cluster Manager Overview
Apache HTTP Server
httpd.conf, Installing and Configuring the Apache HTTP Server
setting up service, Setting Up Apache HTTP Server
availability and data integrity table, Minimum Hardware Requirements

B

backup router
See LVS clustering

C

channel bonding
See Ethernet bonding
chkconfig, Configuring Services on the LVS Routers
cluster
See cluster types
administration, Cluster Administration
checking the configuration, Checking the Cluster Configuration, Using the shutil Utility
daemons, Configuring Cluster Daemons
diagnosing and correcting problems, Diagnosing and Correcting Problems in a Cluster
disabling the cluster software, Disabling the Cluster Software
displaying status, Displaying Cluster and Service Status
name, changing, Changing the Cluster Name
using Red Hat Cluster Manager with Piranha, Using Red Hat Cluster Manager with Piranha
cluster administration, Cluster Administration
backing up the cluster database, Backing Up and Restoring the Cluster Database
changing the cluster name, Changing the Cluster Name
diagnosing and correcting problems in a cluster, Diagnosing and Correcting Problems in a Cluster
disabling the cluster software, Disabling the Cluster Software
displaying cluster and service status, Displaying Cluster and Service Status
modifying cluster event logging, Modifying Cluster Event Logging
modifying the cluster configuration, Modifying the Cluster Configuration
restoring the cluster database, Backing Up and Restoring the Cluster Database
starting and stopping the cluster software, Starting and Stopping the Cluster Software
updating the cluster software, Updating the Cluster Software
cluster command-line utilities, Cluster Command-line Utilities
cluster communication mechanisms, Cluster Communication Mechanisms
cluster configuration, Checking the Cluster Configuration
minimum
example, Minimum Hardware Requirements
modifying, Modifying the Cluster Configuration
reloading, Configuring the Cluster Software
using the shutil utility, Using the shutil Utility
Cluster Configuration Tool
accessing, The Cluster Configuration Tool
and Oracle service, Oracle and the Cluster Configuration Tool
cluster daemons, Configuring Cluster Daemons
membership daemon, Configuring clumembd
quorum daemon, Configuring cluquorumd
service manager daemon, Configuring the clusvcmgrd daemon
cluster database
backing up, Backing Up and Restoring the Cluster Database
restoring, Backing Up and Restoring the Cluster Database
cluster event logging
daemons
cluhbd, Modifying Cluster Event Logging
clupowerd, Modifying Cluster Event Logging
cluquorumd, Modifying Cluster Event Logging
clusvcmgrd, Modifying Cluster Event Logging
severity levels, Modifying Cluster Event Logging
cluster features
administration user interface, Red Hat Cluster Manager Features
application monitoring, Red Hat Cluster Manager Features
data integrity assurance, Red Hat Cluster Manager Features
event logging facility, Red Hat Cluster Manager Features
failover domain
restricted, Red Hat Cluster Manager Features
unrestricted, Red Hat Cluster Manager Features
manual service relocation capabilities, Red Hat Cluster Manager Features
multiple cluster communication methods, Red Hat Cluster Manager Features
no-single-point-of-failure hardware configuration, Red Hat Cluster Manager Features
service configuration framework, Red Hat Cluster Manager Features
service failover capabilities, Red Hat Cluster Manager Features
status monitoring agent, Red Hat Cluster Manager Features
cluster hardware
connecting, Setting Up and Connecting the Cluster Hardware
power controllers, Choosing the Type of Power Controller
setting up, Setting Up and Connecting the Cluster Hardware
cluster hardware tables, Cluster Hardware Components
cluster member hardware table, Cluster Hardware Components
cluster overview, Red Hat Cluster Manager Overview
cluster service, Red Hat Cluster Manager Overview
displaying status, Displaying Cluster and Service Status
cluster services
active-active NFS configuration, NFS Configuration: Active-Active Example
administration, Service Administration
Apache HTTP Server, setting up, Setting Up Apache HTTP Server
httpd.conf, Installing and Configuring the Apache HTTP Server
configuration, Adding a Service to the Cluster, Configuring a Service
configuring service disk storage, Configuring Service Disk Storage
deleting a service, Deleting a Service
disabling a service, Disabling a Service
displaying a service configuration, Displaying a Service Configuration
enabling a service, Enabling a Service
gathering service information, Gathering Service Information
handling a service that fails to start, Handling Failed Services
modifying a service, Modifying a Service
MySQL service, setting up, Setting Up a MySQL Service
NFS caveats, NFS Caveats
NFS client access, NFS Client Access
NFS Druid, Using the NFS Druid
NFS server requirements, NFS Server Requirements
NFS service, setting up, Setting Up an NFS Service
Oracle service, setting up, Setting Up an Oracle Service
Oracle, tuning, Tuning Oracle Service
relocating a service, Relocating a Service
Samba Druid, Using the Samba Druid
Samba operating model, Samba Operating Model
Samba server requirements, Samba Server Requirements
Samba service, setting up, Setting Up a Samba Service
scripts, creating, Creating Service Scripts
smb.conf.sharename file fields, Fields in the smb.conf.sharename File
verifying application software and service scripts, Verifying Application Software and Service Scripts
cluster software
command-line utilities, Cluster Command-line Utilities
disabling, Disabling the Cluster Software
installation and configuration, Cluster Configuration
steps for installing and initializing, Installing the Red Hat Cluster Suite Packages
with rpm, Installation with rpm
with the Package Management Tool, Installation with the Package Management Tool
starting and stopping, Starting and Stopping the Cluster Software
steps for installing and initializing, Installing the Red Hat Cluster Suite Packages
updating, Updating the Cluster Software
version display, Displaying the Cluster Software Version
cluster software installation and configuration, Cluster Configuration
cluster systems, Red Hat Cluster Manager Overview
cluster types
compute-clustering
Beowulf, Technology Overview
definition of, Technology Overview
high-availability clustering, Technology Overview
See also Red Hat Cluster Manager
definition of, Technology Overview
load-balance clustering, Technology Overview
See also LVS clustering
definition of, Technology Overview
overview of, Technology Overview
clusvcadm
using, Using the clusvcadm Utility
common cluster behaviors
2-4 Member cluster, IP tie-breaker, Common Behaviors: 2-4 Member Cluster with IP-based Tie-Breaker
3-5 Member Cluster, Common Behaviors: 3-5 Member Cluster
miscellaneous, Common Behaviors: Miscellaneous
service daemons, Common Behaviors: Cluster Service Daemons
two member disk-based tie-breaker, Common Behaviors: Two Member Cluster with Disk-based Tie-breaker
common cluster behaviors table, Common Cluster Behaviors: General
components
of LVS cluster, Components of an LVS Cluster
compute-clustering
See cluster types
configuration
Red Hat Enterprise Linux, Installing and Configuring Red Hat Enterprise Linux
configuration file
reloading, Configuring the Cluster Software
configuring a service, Configuring a Service
console startup messages
displaying, Displaying Console Startup Messages
console switch, Minimum Hardware Requirements
setting up, Setting Up a Console Switch
console switch hardware table, Cluster Hardware Components
conventions
document, Document Conventions

D

daemons
clulockd
configuring, Configuring Cluster Daemons
clumembd
configuring, Configuring Cluster Daemons
cluquorumd
configuring, Configuring Cluster Daemons
clurmtabd
configuring, Configuring Cluster Daemons
clusvcmgrd
configuring, Configuring Cluster Daemons
database service, Red Hat Cluster Manager Features
databases
MySQL
setting up service, Setting Up a MySQL Service
Oracle
oraclescript example, Setting Up an Oracle Service
setting up, Setting Up an Oracle Service
startdb script example, Setting Up an Oracle Service
stopdb script example, Setting Up an Oracle Service
tuning, Tuning Oracle Service
using Cluster Configuration Tool with, Oracle and the Cluster Configuration Tool
deleting a service, Deleting a Service
diagnosing and correcting problems in a cluster
table, Diagnosing and Correcting Problems in a Cluster
disabling a service, Disabling a Service
disk storage
configuring service disk storage, Configuring Service Disk Storage
displaying a service configuration, Displaying a Service Configuration
displaying console startup messages, Displaying Console Startup Messages
displaying devices configured in the kernel, Displaying Devices Configured in the Kernel

E

enabling a service, Enabling a Service
Ethernet channel bonding
configuring, Configuring Ethernet Channel Bonding
event logging
modifying, Modifying Cluster Event Logging
syslog
configuring, Configuring syslogd Event Logging
examples
minimum cluster configuration, Minimum Hardware Requirements
NFS Druid, Using the NFS Druid
no single point of failure configuration, Minimum Hardware Requirements
oracle script, Setting Up an Oracle Service
Samba Druid, Using the Samba Druid
startdb script, Setting Up an Oracle Service
stopdb script, Setting Up an Oracle Service
using Cluster Configuration Tool to add an Oracle service, Oracle and the Cluster Configuration Tool
ext3, Creating File Systems

F

failover and recover scenarios, Failover and Recovery Scenarios
features, cluster, Red Hat Cluster Manager Features
feedback, Send in Your Feedback
file services
NFS
active-active configuration, NFS Configuration: Active-Active Example
caveats, NFS Caveats
client access, NFS Client Access
NFS Druid, Using the NFS Druid
server requirements, NFS Server Requirements
setting up service, Setting Up an NFS Service
Samba
operating model, Samba Operating Model
Samba Druid, Using the Samba Druid
server requirements, Samba Server Requirements
setting up, Setting Up a Samba Service
file systems
creating, Creating File Systems
FTP, clustering, FTP In an LVS Cluster
See also LVS clustering

G

GFS
cluster archive
configuration, Saving Your Configuration and Next Steps
configuration
with ccs_tool, Saving Your Configuration and Next Steps
GFS Setup Druid, The GFS Setup Druid
and CCS files, Choose Location for CCS Files
cluster name, Cluster Name
configuration, The GFS Setup Druid
configuring cluster members, Cluster Members
fence device configuration, Fence Devices
GULM settings, LOCK_GULM parameters
member configuration, Adding a New Member
post-configuration, Saving Your Configuration and Next Steps
saving configuration, Saving Your Configuration and Next Steps
Grand Unified Lock Manager
See GULM
GULM, LOCK_GULM parameters
configuration with GFS Setup Druid, LOCK_GULM parameters

H

handling a service that fails to start, Handling Failed Services
hardware
installing basic cluster hardware, Installing the Basic Cluster Hardware
hardware configuration
availability considerations, Choosing a Hardware Configuration
choosing a configuration, Choosing a Hardware Configuration
cost restrictions, Choosing a Hardware Configuration
data integrity under all failure conditions, Choosing a Hardware Configuration
minimum, Minimum Hardware Requirements
optional hardware, Minimum Hardware Requirements
performance considerations, Choosing a Hardware Configuration
shared storage requirements, Shared Storage Requirements
hardware information, supplementary, Supplementary Hardware Information
hardware installation
operating system configuration, Hardware Installation and Operating System Configuration
hardware watchdog timer
configuring, Configuring a Hardware Watchdog Timer
hardware watchdog timers, Configuring a Hardware Watchdog Timer
high-availability clustering
See cluster types
hot-standby configuration, Red Hat Cluster Manager Overview
how to use this manual, How To Use This Manual
HTTP services
Apache HTTP Server
httpd.conf, Installing and Configuring the Apache HTTP Server
setting up, Setting Up Apache HTTP Server

I

installation
Red Hat Enterprise Linux, Installing and Configuring Red Hat Enterprise Linux
installing basic cluster hardware, Installing the Basic Cluster Hardware
installing the basic cluster hardware, Installing the Basic Cluster Hardware
introduction, Introduction
cluster features, Red Hat Cluster Manager Features
cluster overview, Red Hat Cluster Manager Overview
how to use this manual, How To Use This Manual
other Red Hat Enterprise Linux manuals, Introduction
iptables, Configuring Services on the LVS Routers
ipvsadm program, ipvsadm

J

job scheduling, LVS, LVS Scheduling Overview

K

kernel
decreasing kernel boot timeout limit, Decreasing the Kernel Boot Timeout Limit
displaying configured devices, Displaying Devices Configured in the Kernel
Kernel Boot Timeout Limit
decreasing, Decreasing the Kernel Boot Timeout Limit
Kimberlite, Acknowledgments
KVM (keyboard, video, mouse) switch, Minimum Hardware Requirements

L

least connections
See job scheduling, LVS
Linux Virtual Server
See LVS clustering
load-balance clustering
See cluster types
low voltage differential (LVD), SCSI Bus Length
LVS
/etc/sysconfig/ha/lvs.cf file, /etc/sysconfig/ha/lvs.cf
components of, Components of an LVS Cluster
daemon, lvs
date replication, real servers, Data Replication and Data Sharing Between Real Servers
definition of, Technology Overview
initial configuration, Initial LVS Configuration
ipvsadm program, ipvsadm
job scheduling, LVS Scheduling Overview
lvs daemon, lvs
LVS routers
configuring services, Initial LVS Configuration
necessary services, Configuring Services on the LVS Routers
primary node, Initial LVS Configuration
multi-port services, Multi-port Services and LVS Clustering
FTP, FTP In an LVS Cluster
nanny daemon, nanny
NAT routing
enabling, Enabling NAT Routing on the LVS Routers
requirements, hardware, The NAT LVS Cluster
requirements, network, The NAT LVS Cluster
requirements, software, The NAT LVS Cluster
overview of, Load-Balancing Clusters Using Linux Virtual Servers, Linux Virtual Server Overview
packet forwarding, Initial LVS Configuration
Piranha Configuration Tool, Piranha Configuration Tool
pulse daemon, pulse
real servers, Load-Balancing Clusters Using Linux Virtual Servers
routing methods
NAT, Routing Methods
routing prerequisites, Configuring Network Interfaces for a NAT LVS Cluster
scheduling, job, LVS Scheduling Overview
send_arp program, send_arp
shared data, Data Replication and Data Sharing Between Real Servers
starting the cluster, Configuring the LVS Routers with Piranha Configuration Tool
synchronizing configuration files, Configuring the LVS Routers with Piranha Configuration Tool
three tiered
Red Hat Cluster Manager, A Three Tiered LVS Configuration
using Red Hat Cluster Manager with Piranha, Using Red Hat Cluster Manager with Piranha
lvs daemon, lvs

M

member status table, Displaying Cluster and Service Status
member systems
See cluster systems
members
setting up, Setting Up the Members
membership daemon, Configuring clumembd
minimum cluster configuration example, Minimum Hardware Requirements
minimum hardware configuration, Minimum Hardware Requirements
Mission Critical Linux, Inc., Acknowledgments
mkfs, Creating File Systems
multi-port services, clustering, Multi-port Services and LVS Clustering
See also LVS clustering
MySQL
setting up service, Setting Up a MySQL Service

N

nanny daemon, nanny
NAT
enabling, Enabling NAT Routing on the LVS Routers
routing methods, LVS, Routing Methods
network address translation
See NAT
network hardware table, Cluster Hardware Components
network hub, Minimum Hardware Requirements
network switch, Minimum Hardware Requirements
NFS
active-active configuration, NFS Configuration: Active-Active Example
caveats, NFS Caveats
client access, NFS Client Access
NFS Druid, Using the NFS Druid
server requirements, NFS Server Requirements
setting up service, Setting Up an NFS Service
NMI watchdog timer
enabling, Enabling the NMI Watchdog Timer
no single point of failure configuration, Minimum Hardware Requirements
Non-Maskable Interrupt (NMI) watchdog timers, Enabling the NMI Watchdog Timer

O

operating system configuration
hardware installation, Hardware Installation and Operating System Configuration
Oracle
adding an Oracle service, Oracle and the Cluster Configuration Tool
oracle script example, Setting Up an Oracle Service
setting up service, Setting Up an Oracle Service
startdb script example, Setting Up an Oracle Service
stopdb script example, Setting Up an Oracle Service
tuning service, Tuning Oracle Service
overview
introduction, Red Hat Cluster Manager Overview

P

packet forwarding, Initial LVS Configuration
See also LVS clustering
Parallel SCSI
requirements, Configuring Shared Disk Storage
parted
creating disk partitions, Partitioning Disks
partitioning disks, Partitioning Disks
Piranha
using Red Hat Cluster Manager with, Using Red Hat Cluster Manager with Piranha
Piranha Configuration Tool, Piranha Configuration Tool
CONTROL/MONITORING, Configuring the LVS Routers with Piranha Configuration Tool
EDIT MONITORING SCRIPTS Subsection, VIRTUAL SERVERS
GLOBAL SETTINGS, Configuring the LVS Routers with Piranha Configuration Tool
limiting access to, Initial LVS Configuration, Limiting Access To the Piranha Configuration Tool
login panel, Configuring the LVS Routers with Piranha Configuration Tool
necessary software, Configuring the LVS Routers with Piranha Configuration Tool
overview of, Configuring the LVS Routers with Piranha Configuration Tool
REAL SERVER subsection, VIRTUAL SERVERS
REDUNDANCY, Configuring the LVS Routers with Piranha Configuration Tool
setting a password, Initial LVS Configuration
VIRTUAL SERVER subsection
Firewall Mark, The VIRTUAL SERVER Subsection
Persistence, The VIRTUAL SERVER Subsection
Scheduling, The VIRTUAL SERVER Subsection
Virtual IP Address, The VIRTUAL SERVER Subsection
VIRTUAL SERVER subsection, VIRTUAL SERVERS
VIRTUAL SERVERS, Configuring the LVS Routers with Piranha Configuration Tool
piranha-gui service, Configuring Services on the LVS Routers
piranha-passwd, Initial LVS Configuration
point-to-point Ethernet connection hardware table, Cluster Hardware Components
power controller connection, configuring, Configuring a Power Controller Connection
power controllers, Choosing the Type of Power Controller
network-attached, Choosing the Type of Power Controller
serial-attached, Choosing the Type of Power Controller
watchdog timers, Choosing the Type of Power Controller
hardware-based, Choosing the Type of Power Controller
software-based, Choosing the Type of Power Controller
power switch, Configuring a Power Controller Connection
See also power controller
power switch hardware table, Cluster Hardware Components
power switches
configuring, Configuring Power Switches
hardware watchdog timers
configuring, Configuring a Hardware Watchdog Timer
NMI watchdog timers
enabling, Enabling the NMI Watchdog Timer
setting up, Setting Up Power Controllers
watchdog, Setting up Watchdog Power Switches
software watchdog timers
configuration, Configuring the Software Watchdog Timer
testing, Testing the Power Switches, Using the clufence Utility
troubleshooting, Testing the Power Switches, Using the clufence Utility
pulse daemon, pulse
pulse service, Configuring Services on the LVS Routers

Q

quorum daemon, Configuring cluquorumd
quorum partitions
See shared cluster partitions
testing, Using the shutil Utility

R

raw, Creating Raw Devices
raw devices
creating, Creating Raw Devices
rawdevices
editing the file, Editing the rawdevices File
real servers
See LVS clustering
configuring services, Initial LVS Configuration
Red Hat Cluster Manager, Technology Overview
and Piranha, Using Red Hat Cluster Manager with Piranha
command-line utilities, Cluster Command-line Utilities
with Red Hat GFS, The GFS Setup Druid
Red Hat Cluster Suite, Installing the Red Hat Cluster Suite Packages
installation, Installing the Red Hat Cluster Suite Packages
with rpm, Installation with rpm
with the Package Management Tool, Installation with the Package Management Tool
Red Hat Enterprise Linux, Introduction to Linux Virtual Server
installation and configuration, Installing and Configuring Red Hat Enterprise Linux
overview of, Technology Overview
Red Hat GFS
and Red Hat Cluster Suite, The GFS Setup Druid
Red Hat GFS with Red Hat Cluster Suite
changes to Red Hat Cluster Suite, Using Red Hat GFS with Red Hat Cluster Suite
installation scenarios, Using Red Hat GFS with Red Hat Cluster Suite
terminology, Using Red Hat GFS with Red Hat Cluster Suite
using, Using Red Hat GFS with Red Hat Cluster Suite
using GFS Setup Druid, The GFS Setup Druid
relocating a service, Relocating a Service
round robin
See job scheduling, LVS
routing
prerequisites for LVS, Configuring Network Interfaces for a NAT LVS Cluster

S

Samba
operating model, Samba Operating Model
Samba Druid, Using the Samba Druid
server requirements, Samba Server Requirements
setting up service, Setting Up a Samba Service
smb.conf.sharename file fields, Fields in the smb.conf.sharename File
scheduling, job (LVS), LVS Scheduling Overview
scripts
creating service scripts, Creating Service Scripts
oracle script example, Setting Up an Oracle Service
startdb script example, Setting Up an Oracle Service
stopdb script example, Setting Up an Oracle Service
verifying application software and service scripts, Verifying Application Software and Service Scripts
SCSI bus configuration requirements, SCSI Bus Configuration Requirements
SCSI bus length, SCSI Bus Length
SCSI bus termination, SCSI Bus Termination
SCSI identification numbers, SCSI Identification Numbers
security
Piranha Configuration Tool, Limiting Access To the Piranha Configuration Tool
send_arp program, send_arp
service configuration, Configuring a Service
service failover, Red Hat Cluster Manager Overview
service property and resource information table, Gathering Service Information
service relocation, Red Hat Cluster Manager Overview
service status table, Displaying Cluster and Service Status
services, Adding a Service to the Cluster
See also adding to the cluster configuration
shared cluster partitions
configuring, Configuring Shared Cluster Partitions
requirements, Configuring Shared Cluster Partitions
shared disk storage
configuring, Configuring Shared Disk Storage
shared disk storage hardware table, Cluster Hardware Components
shared partitions
testing, Testing the Shared Partitions
shared state, Red Hat Cluster Manager Overview
shared storage, Configuring Shared Disk Storage
shared storage requirements, Shared Storage Requirements
single-initiator fibre channel interconnect
setting up, Setting Up a Fibre Channel Interconnect
single-initiator SCSI bus
setting up, Setting Up a Single-initiator SCSI Bus
software information, supplementary, Supplementary Software Information
software watchdog timers, Configuring the Software Watchdog Timer
sshd service, Configuring Services on the LVS Routers
synchronizing configuration files, Configuring the LVS Routers with Piranha Configuration Tool
syslog, Configuring syslogd Event Logging
syslog event logging
configuring, Configuring syslogd Event Logging
syslogd, Configuring syslogd Event Logging
System V init, Starting and Stopping the Cluster Software

T

tables
availability and data integrity, Minimum Hardware Requirements
cluster hardware, Cluster Hardware Components
cluster member hardware, Cluster Hardware Components
common cluster behaviors, Common Cluster Behaviors: General
console switch hardware, Cluster Hardware Components
diagnosing and correcting problems in a cluster, Diagnosing and Correcting Problems in a Cluster
installing the basic cluster hardware, Installing the Basic Cluster Hardware
member status, Displaying Cluster and Service Status
minimum cluster configuration components, Minimum Hardware Requirements
network hardware, Cluster Hardware Components
no single point of failure configuration, Minimum Hardware Requirements
point-to-point Ethernet connection hardware, Cluster Hardware Components
power controller connection, configuring, Configuring a Power Controller Connection
power switch hardware, Cluster Hardware Components
service property and resource information, Gathering Service Information
service status, Displaying Cluster and Service Status
shared disk storage hardware, Cluster Hardware Components
UPS system hardware, Cluster Hardware Components
terminal server, Minimum Hardware Requirements
testing
power switches, Testing the Power Switches, Using the clufence Utility
quorum partitions, Using the shutil Utility
shared partitions, Testing the Shared Partitions
troubleshooting
diagnosing and correcting problems in a cluster, Diagnosing and Correcting Problems in a Cluster
failover and recover scenarios, Failover and Recovery Scenarios
power switch testing, Testing the Power Switches, Using the clufence Utility
table, Diagnosing and Correcting Problems in a Cluster

U

UPS system hardware table, Cluster Hardware Components
UPS systems
configuring, Configuring UPS Systems
using Red Hat GFS with Red Hat Cluster Suite, Using Red Hat GFS with Red Hat Cluster Suite
utilities
clufence, Using the clufence Utility
clusvcadm, Using the clusvcadm Utility
redhat-config-cluster-cmd, Using redhat-config-cluster-cmd
shutil, Using the shutil Utility

W

watchdog timers
hardware
configuring, Configuring a Hardware Watchdog Timer
hardware-based, Choosing the Type of Power Controller
NMI
enabling, Enabling the NMI Watchdog Timer
setting up, Setting up Watchdog Power Switches
software, Configuring the Software Watchdog Timer
configuration, Configuring the Software Watchdog Timer
software-based, Choosing the Type of Power Controller
weighted least connections
See job scheduling, LVS
weighted round robin
See job scheduling, LVS