、1 (課程博士(英文))牙1俳氏4Date of submission (mon壮l day, year)

January 9,2018

DeP加如ent

Computer science

StudentlD Number

D149301and En部neering
Pplicant s nameYosh北eru lshida
Supervisors

Jun Miura

Idris winaTno

Abstract (Doctor)
Title ofThesis

A Resilient server W辻h a self・Repair Network Modelon the vi此Ualization
EnV辻onment

Approx.80o words

The peTformance of an information system depends on the reliability of thedata center infrastructure. A computer w'hich has a high specification and runs aService, which can be accessed by multiple users over a network,is ca11ed a server.

The server is one ofthe most critical parts of a data center, hence can negativel
affect the overa11 Performance of an information system in cases of system failure(e.g. hang faulty, denial of seぞVice attack, and malware). since servers play a
Cr此ical role in data processing and data transmission for serving many clients,
failures in servers cause not only performance degradation ofthe server 北SeH but
also threats to the entire computer connected to the servers. Resilient servers thatCan self、recognize failures, self'repair failures and seH・replace failed arts arerequired when computersystems and networks become huge・scale as W北nessed bydata centers and the cloud computing. Recen目y, virtualization has become aPopular method to develop servers for data centeぞ infrastructure. Thus, we re uirea modelthat can deal W北h virtualservers as a repair unit. TheTe are two t es ofVirtualization techn010gy that we can use to build the resilient server:
Virtualization machine monitor (VMM) and container (also ca11ed as Linux
Container or LXC). container offers fast boot and efficient Tesource usage todeploy a sel'ver on the virtual environment. However, VMM PI・ovides hi herdiversity of guest operating system than container.
In this study, we introduce a new model of the resilient server b

implementing a seH、repair network (SRN) model in the virtualization

environment to address failUぞes that occur during the operation ofthe server. TheSRN model offers a geneTal framework of self・action models for tbe servet toSelf、recognize, self、repair, and self、replace its own failed parts aearned fl.om

.

imlnune system).1n this study we use the f0110wing four models of sRN:(DSelf、repair,(iD mutual、repair,(iii) mixed・repair, and GV) switcbing・repair. The
SRN model wi11 be applied to the script that we ca11ed as sRN mana er. This

Script has the main responsibi1北y to mon北or and respond to the failures. X入ledefine ei今ht types of resilient server using the combination of three arameters

induding application (service), guest operating system, and host operating system(virtualization en弩ine).
The simulations show that virtualization techn010gy is able to build a resilient
Server to recover the failure in the lim北ed scenario. The fiぞSt ex eriment showsthat container outperforms the vMM since container almost ten times faster andmore efacient of memory resources compared to the vMM. However, a container

has lower diversity than vM入l due to container uses a shared kernel. The sec。 dexperiment explains that a resilient server with a homogeneous environment
Offers ease of replacement of the failed parts, but this resilient server has lesresilience than those with heterogeneous environment since the entire serve 'n

the homogenous environment has the same vulnerabi1北y. The last ex eri t
describes that we use multiple virtuaHzation engines to increase the divers't f

the resilient server. Moreover, the performance of our proposed method has l。
Perfonnance losses and bigh service availability.