Linux Virtual Server for Scalable Network Services

Copyright © 2002 Wensong Zhang. Page 1

Free Software Symposium 2002

Linux Virtual Server: Linux Linux Virtual Server: Linux Server Clusters for Scalable Server Clusters for Scalable Network ServicesNetwork Services

Wensong ZhangWensong Zhang

China National Laboratory for Parallel & China National Laboratory for Parallel & Distributed ProcessingDistributed Processing

Free Software Symposium 2002Free Software Symposium 2002

October 22, 2002October 22, 2002



AgendaAgenda

IntroductionIntroductionThe Linux Virtual Server frameworkThe Linux Virtual Server frameworkBuilding Scalable Network Services Building Scalable Network Services

using LVSusing LVSFuture Work of LVSFuture Work of LVSCharacteristics of LVSCharacteristics of LVS



IntroductionIntroduction InternetInternetExplosive Growth of the InternetExplosive Growth of the Internet

–100% annual growth rate100% annual growth rate

Sites receiving unprecedented Sites receiving unprecedented workloadworkload–Yahoo! 625 million views per dayYahoo! 625 million views per day

–AOL Web cache system receiving 5 AOL Web cache system receiving 5 billion requests per daybillion requests per day


Free Software Symposium 2002IntroductionIntroduction

The requirements of The requirements of Network ServicesNetwork ServicesIncremental scalabilityIncremental scalability24x7 availability24x7 availabilityManageabilityManageabilityCost-effectivenessCost-effectiveness



IntroductionIntroduction Possible SolutionsPossible SolutionsSingle server upgradeSingle server upgrade

–complicated, high cost, single point of complicated, high cost, single point of failure, ...failure, ...

Cluster of servers is becoming a Cluster of servers is becoming a viable architecture for SNSviable architecture for SNS–Redundancy --> HARedundancy --> HA

–Divide-and-Conquer --> High-performanceDivide-and-Conquer --> High-performance

–High performance/cost ratioHigh performance/cost ratio


Free Software Symposium 2002LVS FrameworkLVS Framework

The Linux Virtual The Linux Virtual Server ProjectServer ProjectThe goal of the Linux Virtual Server The goal of the Linux Virtual Server

projectproject– to provide a basic framework for building to provide a basic framework for building

highly scalable and highly available highly scalable and highly available network services using a large cluster of network services using a large cluster of commodity servers.commodity servers.



LVS FrameworkLVS Framework FrameworkFramework



IPVS is an advanced Layer-4 switchingIPVS is an advanced Layer-4 switching

LVS FrameworkLVS Framework IP Virtual ServerIP Virtual ServerImplemented in the Linux kernelImplemented in the Linux kernelThree IP load balancing techniquesThree IP load balancing techniques

–Virtual Server via NATVirtual Server via NAT

–Virtual Server via IP TunnelingVirtual Server via IP Tunneling

–Virtual Server via Direct RoutingVirtual Server via Direct Routing

Eight scheduling algorithmsEight scheduling algorithms



LVS FrameworkLVS Framework VS/NATVS/NAT



LVS FrameworkLVS Framework VS/TUNVS/TUN



LVS FrameworkLVS Framework VS/DRVS/DR



LVS FrameworkLVS Framework ComparisonComparison

VS/ NAT VS/ TUN VS/ DR

Server any Tunneling Non-arp device

server network private LAN/ WAN LAN

server number low (10~20) High (100) High (100)

server gateway load balancer own router Own router

Note: those numbers are estimated based on the assumption that load balancer and backend servers have the same hardware configuration.



LVS FrameworkLVS Framework Scheduling AlgorithmsScheduling AlgorithmsRound-RobinRound-RobinWeighted Round-RobinWeighted Round-RobinLeast-ConnectionLeast-ConnectionWeighted Least-ConnectionWeighted Least-Connection



Scheduling Algorithms Scheduling Algorithms (Continued)(Continued)Locality-Based Least-ConnectionLocality-Based Least-ConnectionLocality-Based Least-Connection with Locality-Based Least-Connection with

ReplicationReplicationSource HashingSource HashingDestination HashingDestination Hashing



LVS FrameworkLVS Framework State SynchronizationState Synchronization

Conn Sync daemon (kernel thread)Conn Sync daemon (kernel thread)UDP MulticastUDP Multicast



Layer-7 switching in user-spaceLayer-7 switching in user-space–high overhead of context switching and high overhead of context switching and

memory copyingmemory copying

– limited scalabilitylimited scalability

LVS FrameworkLVS Framework KTCPVSKTCPVS



kernel threadkernel threadloadable scheduling moduleloadable scheduling module

LVS FrameworkLVS Framework KTCPVS (Cont’d)KTCPVS (Cont’d)



Cluster Monitoring Cluster Monitoring softwaresoftwareRed Hat Cluster Server / PiranhaRed Hat Cluster Server / Piranha

–LVS + PiranhaLVS + Piranha

UltraMonkeyUltraMonkey–LVS + lvs-gui + heartbeat + ldirectordLVS + lvs-gui + heartbeat + ldirectord

KeepalivedKeepalivedNetparseNetparseetc.etc.



Building SNS using LVSBuilding SNS using LVS General ArchitectureGeneral Architecture

3 3 tierstiers–Load balancerLoad balancer

–Server clusterServer cluster

–Shared storageShared storage



Building SNS using LVSBuilding SNS using LVS Building BlocksBuilding BlocksLoad balancerLoad balancer

–Layer-4 switching, Layer-7 switchingLayer-4 switching, Layer-7 switching

ServerServer–HTTP, HTTPS, FTP, SMTP, POP3, IMAP4, HTTP, HTTPS, FTP, SMTP, POP3, IMAP4,

most TCP and UDP servicesmost TCP and UDP services

Shared storageShared storage–database, network file system, distributed database, network file system, distributed

file system, ...file system, ...



Building SNS using LVSBuilding SNS using LVS High AvailabilityHigh AvailabilityServer failoverServer failover

–ping, service detection, etcping, service detection, etc

Load balancer failoverLoad balancer failover–state synchronizationstate synchronization

–heartbeatheartbeat



Building SNS using LVSBuilding SNS using LVS Web ClusterWeb Cluster



Building SNS using LVSBuilding SNS using LVS Cache ClusterCache Cluster



Building SNS using LVSBuilding SNS using LVS Mail ClusterMail Cluster



Building SNS using LVSBuilding SNS using LVS Some Sites using LVSSome Sites using LVSUK National JANET Web Cache UK National JANET Web Cache

(wwwcache.ja.net)(wwwcache.ja.net)linux.comlinux.comsourceforge.netsourceforge.netvalinux.comvalinux.comreal.comreal.comOne of largest PC manufacturersOne of largest PC manufacturersetc.etc.



Future Works of LVSFuture Works of LVS Future WorksFuture WorksAdding more load balancing Adding more load balancing

algorithmsalgorithmsDeveloping more advanced/flexible Developing more advanced/flexible

cluster monitoring softwarecluster monitoring softwareMaking KTCPVS ready for productionMaking KTCPVS ready for productionExploring TCP handoffExploring TCP handoffetc.etc.



Characteristics of LVSCharacteristics of LVS

CharacteristicsCharacteristicsLVS extends Linux kernel to support LVS extends Linux kernel to support

three IP load balancing techniquesthree IP load balancing techniquesEight scheduling algorithmsEight scheduling algorithmsHigh scalability (up to 100 nodes)High scalability (up to 100 nodes)High availabilityHigh availabilitySupporting most TCP and UDP Supporting most TCP and UDP

services, no modifications to either services, no modifications to either clients or serversclients or servers


Free Software Symposium 2002Characteristics of LVSCharacteristics of LVS

Compared to Other Compared to Other Commercial ProductsCommercial ProductsMore IP load balancing techniquesMore IP load balancing techniquesMultiple scheduling algorithmsMultiple scheduling algorithmsState synchronizationState synchronizationA robust and stable code base, a large A robust and stable code base, a large

user and developer base.user and developer base.Reliability proven in big real world Reliability proven in big real world

applicationsapplicationsFree to everyoneFree to everyone



SummarySummary

IntroductionIntroductionThe Linux Virtual Server frameworkThe Linux Virtual Server frameworkBuilding Scalable Network Services Building Scalable Network Services

using LVSusing LVSFuture Work of LVSFuture Work of LVSCharacteristics of LVSCharacteristics of LVS



Call to ActionCall to Action

Building scalable network services is Building scalable network services is complicated and expensivecomplicated and expensive

LVS is here to help make your life LVS is here to help make your life easiereasier

LVS is proven stable, and is being LVS is proven stable, and is being deployed by more and more sites.deployed by more and more sites.



CollateralCollateral

The Linux Virtual Server ProjectThe Linux Virtual Server Project

(http://www.LinuxVirtualServer.org)(http://www.LinuxVirtualServer.org)

[email protected]@linux-vs.org

Technology

Linux Virtual Server for Scalable Network Services