COMMA: Coordinating the Migration of Multi-tier ApplicationsJie Zheng, T. S. Eugene Ng, Zhaolei LiuRice University

Kunwadee SripanidkulchaiNECTEC, Thailand

VEE’14

MotivationLive migration can migrate single

VM efficiently.Existing solutions on migrating

VMs in a multi-tier application can cause serious performance degradation.

Multi-tier Application

Split-components Problem

Existing Solutions

Problem FormulationGiven a set of n VMs in a multi-

tier application.Minimize the performance

degradation, or impact.

◦TM[i,j]: communication traffic rates between VMs prior to the start of migration.

n

i

n

ijji jiTMttimpact

1

,

COMMA“COordinating the Migration of

Multi-tier Applications”◦The first migration coordination

system for multiple VMs.◦Centralized architecture.◦A two-stage scheduling.

Two-stage SchedulingFirst stage: migrates static

content.Second stage : migrate

dynamically generated content.

First StageMigrate VMs in parallel and finish

all VMs’ data migration at the same time.◦The amount of migrated data is

fixed.Adjusts each VM’s migration

speed according to its virtual disk size _SIZETOTAL_DISK

BANDWIDTH*DISK_SIZEivmi

speed

Second StageMigrate dynamically generated

content.◦After the first stage, a set of dirty

blocks are recorded.◦The minimum migration speed of a

VM must be greater than its block dirty rate.

VMs are divided into groups.BANDWIDTH}rateMax_dirty_{

groupvmi

i

Inter-group SchedulingTo minimize the impact.Brute-force

◦O(2n*n!)

Inter-group Scheduling(Cont.)To minimize the impact.Heuristic

◦Repeatedly take the largest rate element (rate, VMi, VMj) from the list L, check if VMi and VMj are already in the group set S. Merge group or insert new groups.

◦Find the permutation of groups in S with minimal impact

◦O(n!)

Intra-group SchedulingStarting the VMs’ migration at

the same time is not an efficient use of available migration bandwidth.

Intra-group Scheduling(Cont.)Estimate the migration time of each

VM.◦Assume the minimal required speed for

each VM is equal to the VM’s maximal dirty rate

“Finish migration at the same time”◦Set different start time to each VM.

Extra available bandwidth will be allocated to the VMs to minimize the total migration time of the group.

Evaluation-SettingSix physical machines.Kernel-based Virtual

Machine(KVM)Multi-tier application: RUBiS

◦Includes web server, application server, database server.

Performance metric: average response time of the request from clients per second.

Migrate 3VMs with different strategies.

Evaluation-Performance

Evaluation-ImpactMigrate 4 VMs from at most three

physical machines to the other three.

Evaluation-EC2Migrate 2 SPECweb2005 VMs

from a university campus network to EC2 instances.

ConclusionPropose COMMA, the first

coordinated live VM migration system for multi-tier applications.◦Based on a two-stage scheduling

algorithm to coordinate the migration of VMs.

◦The goal is to minimize the migration’s impact on inter-component communications.