Classifying Algorithm Based on a Fuzzy Neural network for the control of a Network Attached Opti
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OPTOELECTRONICS LE|TTERS VoI 2 No 6。15 Nov.2006
LIU Xuan ,JIA Hui-bo,and CHENG Ming
Optical Memory National Engineering Research Center,Tsing ̄a
(Received 25 August 2006)
A new anal、,ticaI method for improving the performance of a network a ̄ached opticaIjukebox is pres- ented by means of artificiaI neuraI networks.Through analyzing operation(request)process in this sys-
tem,the mathematics modeI and algoritl ̄n are built for this storage system,and then a classified meth-
od based on artificiaI neuraI networks for this system is proposed.Simulation results testified the feasi-
billty and vaIidity of the proposed method that it could overcome the drawbacks of the frequent I/0 op-
eration and provide an effective way for using the Network Attached OpticaI Jukebox.
CLC number:TP183 I:)ocum ̄nt cOde:A Article lD:1673.1905(2006)06—0459-04
In our previOUS work[ 一引,we established a new ap—
proach which has mass disk buffer in optical i ukebox
and can be accessed directly from network in a mass
storage system,and named this system as network atta—
ched optical j ukebox(NAOJ).In order to improve its
performance further,a new approach based on a fuzzy
artificial neural network is presented in this letter.
As we usually know,the network surrounding is very
complicated,and the optical jukebox has its disadvantage
due to mechanical movement,which limits its applica-
tion.In order to improve its access speed it is necessary to analyze different cases in the application models for
the Network Attached Optical Jukebox. In this paper,we firstly establish a preferential queu~
ing network model for NAOJ,and then based on this
model we use a neural network method to classify the
users requests.The simulation results testified the feasi-
bility and validity of the proposed method that it could
overcome the drawbtLcks of the frequent I/0 operation
and provide an effective way for using NAOJ.
The storage model of NAOJ consists of a network
service module,a magnetic disk cache module and an op-
tical i ukebox module.The framework is shown in Fig.1.
IDE magnetic
1 The queuing model for Network Attad ̄Optie ̄Juke-
box
* E-mail:liu2xuan99@mails.tsinghua.edu.cn For one operation(request)from I/O port,the net—
work service module needs to complete two actions,i.e.
receiving the user request and seeding required data to
the user[ .The NAOJ will complete the following steps
for each request.
According to the operation principle of Network Atta— ched Optical Jukebox ̄ and the idea of hierarchical stor—
age system,when an accessing request comes,it first
searches in the disk cache.If the data needed is not
stored in the disk cache,we will access the optical j uke—
box.At this time.the data that the user needs may be
any one under the three situations below:
1.The data are being transferred to another user,
which means the data are hot in this period,but it was
not prefetched to the disk cache before.Therefore,the
situation is that the other userg requests come when the
data are transferring to the first user;
2.The data are not being transferred,but it is stored
in the disk placed in the driver;
3.The data are not stored in the disk placed in the
driver.
However,the hit rate of that the data are right in the
disk cache is quite limited,because it is correlated with
the user accessing distributing,demanded data quantity
and many other factors.This leads to that the accessing
to the optical iukebox is still more frequent.As the re—
sult,a great part of the optical jukebox response time
wastes on the machine operation such as change disks.
Therefore,a further study on the user s accessing will
make great help to the improvement of the whole sys—
tem De ̄ormance of Network Attached Optical Jukebox.
Userg requests are partitioned into N levels.The first
level has the highest priority,and will be dealt with
firstly by the storage management server.The second
level has the secondary priority.And the N-th level has
the lowest priority and U be dealt with lastly.
A non-preemptive priority queuing model,that i
s,if 维普资讯 http://www.cqvip.com ・0460・
the system is busy the users request that has the priori—
ty can t preempt the service window,but queue before the lower-or-non priority reques{ , .
Assume that is the arriving rate of the i level, is
the average request access service rate of the i level,Ti
is the service time for the request of the i level where 1
N,and is the average arriving rate of all the re—
quire.Obviously we only know as a parameter in this
model because is not surveyed in real circumstance.
Then we have
T【 一 1 』£=E1 l一一
Let 一 t/ 一 Ti.Since the requests of Ist to N lev—