KR101063837B1 - Disk Management Method for Reducing Energy Consumption in Multi-Speed Disk Array-based Video Servers - Google Patents

Abstract

} 및 버퍼 이용도{

}를 산출하는 단계, (c) 복수의 전력 모드에 기초하여, 각 디스크(k)의 상기 설정된 레벨(j,m)에 따른 전체 소비 에너지{

}를 산출하는 단계, (d) 상기 각 디스크(k) 별로, 상기 디스크 대역폭 이용도{

}가 1 이하인, 상기 라운드 길이 레벨(j) 및 상기 디스크 스피드 레벨(m)의 쌍을 원소로 갖는 제 1 집합(

)을 생성하는 단계, (e) 상기 제 1 집합의 상기 원소를, 상기 산출된 전체 소비 에너지{

} 값에 기초하여, 내림차순으로 정렬하는 단계, (f) 상기 제 1 집합의 정렬된 각 원소(l)에 대하여, 상기 정렬된 첫번째 원소에 대한 절감 전력{

}을 산출하는 단계, (g) 제 1 집합의 정렬된 각 원소(l)에 대하여, 상기 버퍼 이용도 변화율에 대한 상기 절감 전력의 변화율 값{

}을 산출하여 제 2 집합(SG)을 생성하는 단계, (h) 임시 변수 TE 값을 초기화하는 단계, (i) 상기 제 1 집합에서

번째 원소를 선택하고, 상기 선택된 원소의 라운드 길이 레벨(j) 및 디스크 회전 속도 레벨(m)을 초기화하는 단계, (j) 상기 제 2 집합에서, 값이 가장 큰 원소{

}를 상기 제 2 집합에서 제거하는 단계, (k) 상기 제 2 집합에서 값이 가장 큰 원소의 번호(h), 상기 임시 변수 TE, 상기 선택된

번째 원소에서의 버퍼 이용도 및 상기 제 2 집합에서 값이 가장 큰 원소의 번호(h)에서의 버퍼 이용도에 기초하여, 상기 임시 변수 TE, 상기 선택된

번째 원소의 라운드 길이 레벨 값 및 상기 선택된

번째 원소의 디스크 회전 속도 레벨 값을 변경하는 단계 및, (l) 상기 제 2 집합의 원소 개수가 2 이상일 경우, 상기 (j) 단계 내지 (k) 단계를 반복하는 단계를 포함한다.Disc management method for reducing energy consumption in a multi-rate disk array based video server is provided. Disc management method for reducing energy consumption in a multi-rate disk array based video server comprises the steps of (a) setting the level (m) of the disk rotation speed and the level (j) of the round length, (b) each disk (k) Disk bandwidth utilization by

} And buffer utilization {

}, (C) based on the plurality of power modes, the total energy consumed according to the set level (j, m) of each disk (k) {

}, (D) for each disk k, the disk bandwidth utilization {

The first set having as its elements a pair of the round length level (j) and the disk speed level (m), wherein

), (E) replacing the element of the first set with the calculated total energy consumption {

} Sorting in descending order based on a value, (f) for each ordered element (l) of the first set, the power savings for the first ordered element {

} Calculating (g) for each element l sorted in the first set, the rate of change of the power savings relative to the rate of change of buffer utilization {

} To generate a second set SG, (h) initializing a temporary variable TE value, and (i) in the first set.

Selecting the second element and initializing the round length level (j) and the disk rotational speed level (m) of the selected element, (j) in the second set, the element having the largest value {

} Is removed from the second set, (k) the number (h) of the element with the largest value in the second set, the temporary variable TE, the selected

Based on the buffer utilization at the first element and the buffer utilization at the number h of the element with the largest value in the second set, the temporary variable TE, the selected

The round length level value of the first element and the selected

Changing the disk rotation speed level value of the second element, and (l) repeating steps (j) to (k) when the number of elements of the second set is two or more.

Round length, disk rotation speed, buffer utilization, bandwidth utilization, energy consumption

Description

DISK MANAGEMENT METHOD FOR REDUCING DISK ENERGY CONSUMPTION IN MULTI-SPEED-DISK-ARRAY-BASED VIDEO SERVERS}

The present invention relates to a disk management method for reducing energy consumption in a multi-rate disk array based video server. More particularly, the present invention relates to a rotation speed and a round speed of each disk while satisfying both a buffer limit and a disk bandwidth limit of a video server. Disclosed is a disk management method for reducing energy consumption in a multi-rate disk array based video server by dynamically allocating length, thereby reducing energy consumption in a video server.

The development of Internet-based services is driving the growth of data centers, and data storage is one of the largest components in data centers. Recently, the demand for video contents is increasing, and accordingly, the demand for storage space is increasing by 60% per year. In particular, multimedia data require high bandwidth and large storage space, and the development of various video application services such as digital libraries, distance learning, and user created contents (UCC) has recently increased. This growing demand for data makes server power consumption a critical issue.

Due to the increasing demand for multimedia data, energy consumption of servers has become an important issue. Recently, Energy User News reports that typical service providers currently require 150-200 W / ft2 of power, and in the near future will require 200-300 W / ft2. This growing demand for electricity creates serious economic problems for service providers. For example, a medium sized 30,000 ft2 data center would require 15 MW, which would cost $ 13,000,000 annually. Another problem with high power consumption is the generation of heat. It has been reported that the failure rate of a disk drive can double as high as 15 ° C above standby. To address this, cooling systems for high thermal densities are enormously expensive and the cooling system itself adds significantly to the power costs of the data center.

Because video data requires high bandwidth and large storage space, video servers are typically built on disk arrays that can consist of hundreds of disks. And for servers, storage is one of the most energy consuming components. According to a recent report, storage devices consume about 27% of the total power. In addition, the energy consumed by the disk array has been shown to exceed the energy consumed in the rest of the system, depending on the size of the array. For example, for the EMC Symmetrix 3000, disks account for 86% of the total energy consumption. In the case of the Dell Power Edge6650 benchmark system, the disk consumes 71% of the total power. In particular, this problem can be exacerbated by the availability of higher speed disks that require more power.

Recently, with the development of multimedia applications such as digital libraries, video on demand (VOD), user created contents (UCC), education-on-demand (UDC), and DMB, the proportion of multimedia servers is increasing. For example, YouTube currently serves 40 million videos per day, equivalent to 200TB of data. In addition, recent newspapers and news sites provide news in the form of videos, and new video / audio content is updated on a daily VOD server. As Google recently launched a web video search service and IPTV has been activated, energy reduction in video storage servers is important.

To reduce power consumption, existing disks have multiple power modes that include several power consumption modes, depending on the state of the disk. In active mode, platters are spinning and the head is reading or writing data. In seek mode, the head is searching. In idle mode, the disc rotates at full speed, but there is no processing of the disc request. In the standby mode, the disc stops spinning completely and consumes much less energy than in any other mode. A commonly used method to reduce energy consumption is to put the disk in idle mode after a brief idle state. However, switching to the standby mode requires a lot of energy and time, and because the standby mode cannot process user requests, it is almost impossible to enter the standby mode while reading video data, and the length of the video usually exceeds one hour. Since it is long enough, such a power saving method cannot be easily applied to a video server.

One way to reduce the power consumption of the disk is to reduce the speed at which the disk spins. Gurumurthi et al. Proposed a dynamic multi-speed disk model that can vary the speed during rotation using these characteristics. Using such a disk can significantly reduce power consumption even under intense server workloads. However, existing approaches to reduce disk power consumption by utilizing multiple speeds are mostly based on monitoring the length of the disk request queue and varying the speed of the disk so that the response time for requests remains within a predetermined range. In addition, this method has a problem that is difficult to apply to a video server having a continuous and real-time characteristics.

Therefore, there is a strong demand for a technology that effectively reduces disk power consumption by utilizing a multi-speed feature in a recently activated video server.

Some embodiments of the present invention provide a disk management method for reducing energy consumption in a disk array based video server that can effectively select the level of disk rotation speed and round length to minimize multi-speed disk consumption energy.

} 및 버퍼 이용도{

}를 산출하는 단계, (c) 복수의 전력 모드에 기초하여, 각 디스크(k)의 상기 설정된 레벨(j,m)에 따른 전체 소비 에너지{

}를 산출하는 단계, (d) 상기 각 디스크(k) 별로, 상기 디스크 대역폭 이용도{

}가 1 이하인, 상기 라운드 길이 레벨(j) 및 상기 디스크 스피드 레벨(m)의 쌍을 원소로 갖는 제 1 집합(

)을 생성하는 단계, (e) 상기 제 1 집합의 상기 원소를, 상기 산출된 전체 소비 에너지{

} 값에 기초하 여, 내림차순으로 정렬하는 단계, (f) 상기 제 1 집합의 정렬된 각 원소(l)에 대하여, 상기 정렬된 첫번째 원소에 대한 절감 전력{

}을 산출하는 단계, (g) 제 1 집합의 정렬된 각 원소(l)에 대하여, 상기 버퍼 이용도 변화율에 대한 상기 절감 전력의 변화율 값{

}을 산출하여 제 2 집합(SG)을 생성하는 단계, (h) 임시 변수 TE 값을 초기화하는 단계, (i) 상기 제 1 집합에서

번째 원소를 선택하고, 상기 선택된 원소의 라운드 길이 레벨(j) 및 디스크 회전 속도 레벨(m)을 초기화하는 단계, (j) 상기 제 2 집합에서, 값이 가장 큰 원소{

}를 상기 제 2 집합에서 제거하는 단계, (k) 상기 제 2 집합에서 값이 가장 큰 원소의 번호(h), 상기 임시 변수 TE, 상기 선택된

번째 원소에서의 버퍼 이용도 및 상기 제 2 집합에서 값이 가장 큰 원소의 번호(h)에서의 버퍼 이용도에 기초하여, 상기 임시 변수 TE, 상기 선택된

번째 원소의 라운드 길이 레벨 값 및 상기 선택된

번째 원소의 디스크 회전 속도 레벨 값을 변경하는 단계 및, (l) 상기 제 2 집합의 원소 개수가 2 이상일 경우, 상기 (j) 단계 내지 (k) 단계를 반복하는 단계를 포함하는, 디스크 배열 기반 비디오 서버에서의 에너지 소모 감소를 위한 디스크 관리 방법을 제공할 수 있다.As a technical means for achieving the above-described technical problem, the first aspect of the present invention, (a) setting the level (m) of the disk rotation speed and the level (j) of the round length, (b) each disk ( k) disk bandwidth utilization by {

} And buffer utilization {

}, (C) based on the plurality of power modes, the total energy consumed according to the set level (j, m) of each disk (k) {

} (D) for each disk (k), the disk bandwidth utilization {

The first set having as its elements a pair of the round length level (j) and the disk speed level (m), wherein

), (E) replacing the element of the first set with the calculated total energy consumption {

} Sorting in descending order based on the value, (f) for each ordered element (l) of the first set, the power savings for the first ordered element {

} Calculating (g) for each element l sorted in the first set, the rate of change of the power savings relative to the rate of change of buffer utilization {

} To generate a second set SG, (h) initializing a temporary variable TE value, and (i) in the first set.

Selecting the second element and initializing the round length level (j) and the disk rotational speed level (m) of the selected element, (j) in the second set, the element having the largest value {

} Is removed from the second set, (k) the number (h) of the element with the largest value in the second set, the temporary variable TE, the selected

Based on the buffer utilization at the first element and the buffer utilization at the number h of the element with the largest value in the second set, the temporary variable TE, the selected

The round length level value of the first element and the selected

Changing the disk rotation speed level value of the first element; and (l) repeating steps (j) to (k) when the number of elements in the second set is two or more. A disk management method for reducing energy consumption in a video server can be provided.

According to the above-described problem solving means of the present invention, the disk rotation speed and the round length of the video server is dynamically allocated, thereby effectively reducing the disk consumption energy.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated.

In addition, one embodiment of the present invention uses 'round' based scheduling for data retrieval to support multiple customers. That is, after time is divided into equally sized periods called 'rounds', each authorized customer is served once in each round. In general, video data has real-time requirements and can only be used if the video frame is retrieved before play time. To ensure continuous playback, the data required for the current playback must be read from the disc in the previous round, and the data to be played in the next round is read during the current round. This means that in order to ensure continuous playback, the service time (ie the total time spent searching for all streams during a round) must not exceed the duration of one round. In addition, disk bandwidth utilization is obtained by dividing the service time by the round duration.

In addition, in an embodiment of the present invention, blocks constituting one video file may be continuously stored. Most operating systems use this approach, and especially for video servers, because of the read workload, a contiguous block storage method can be used.

Hereinafter, a disk management method for reducing energy consumption in a disk array based video server according to an embodiment of the present invention will be described in detail.

First, assuming that the set of round lengths and the set of disk speeds supported by the system are sorted in ascending order, the disk bandwidth when the j th level round length and the m th level speed (disk rotation speed) are selected in each set We look at utilization, buffer utilization, and energy consumed by each disk.

For example, if the set of round lengths is {BR, BR + u, BR + 2 * u, BR + 3 * u, BR + 4 * u} and the second round length level is selected, BR + u is the round length Can be selected as. Further, for example, if the set of disk speeds is {7200 rpm, 28800 rpm, 39600 rpm, 72000 rpm} and the third speed level is selected, 39600 rpm can be selected as the disk speed.

)으로 분할한 후, 그룹

내의 고객들이 대응하는 디스크 k로부터 스트림을 수신 받도록 구성되며, 고객

이 상기 비디오 스트림 Vi를 요청하고 있는 비디오 서버에서, 라운드 길이 레벨 j이고, 디스크 회전 속도 레벨이 m 인 경우의 k 번째 디스크에 대한 디스크 대역폭 이용도

와 버퍼 이용도

가 각각 수학식 1 및 2와 같이 계산될 수 있다.When the buffer size is B, the round length at disk's round length level j is Rj, and the disk rotation speed level is m, the power required to perform one read, the power to write data, and the power consumed in idle mode Power consumed in power and low power modes are Ps (m), Pa (m), Pi (m), and Pl (m), respectively, and the transfer rate and disk rotation delay time are tr (m) and Td (m), the disk seek time is a constant Ts, the bit rate of the data of the video stream Vi is dri, the unit is bits / sec, the block size of the disk is bs, One disk has NS speed levels, the disk array consists of NC disks, and the customers have NC customer groups (

After dividing by),

Are configured to receive streams from the corresponding disk k in the

In the video server requesting the video stream Vi, the disk bandwidth utilization for the kth disk when the round length level j and the disk rotation speed level m is also used.

And buffer utilization

May be calculated as Equations 1 and 2, respectively.

&Quot; (1) "

<Equation 2>

Then calculate how the energy consumption depends on the round length level j and the speed level m. Ps is the power required to perform one search in seek mode, Pa is the power required to read or write data in active mode, and Pi is consumed in idle mode. It is power, and Pl is power consumed in a low power mode (standby mode). In this case, the following energy characteristics can be formulated for the disk k.

이며, 따라서 Rj 동안 탐색을 수행하기 위해 요구되는 에너지(

)는

이다.1. The total seek time during Rj is

Therefore, the energy required to perform the search during Rj (

)

to be.

)는

이다.2. The energy required for reading during Rj (

)

to be.

)는 다음의 수학식 3과 같이 표현될 수 있다.3. The energy consumed when no disk activity occurs or when the disk is waiting for some sector to reach under the head.

) May be expressed as Equation 3 below.

&Quot; (3) &quot;

)가 라운드 길이 Rj에 따라 다음 수학식 4와 같이 달라질 수 있다.Based on the above expression, the total energy consumption during

) May vary according to Equation 4 according to the round length Rj.

<Equation 4>

In an embodiment of the present invention, the disk rotation speed and the round length of the video server are dynamically allocated, and in the above model, the energy consumed by the disk can be minimized as follows.

Justice. Round length and speed selection issues ( The Round Length and Speed Selection  Problem; RLSS )

을 만족시키면서

를 최소화하는

에 속한 원소 쌍 (

,)를 찾는 것이다.RLSS limits buffers for all disks k (k = 1,…, NC)

While satisfying

To minimize

Element pairs belonging to (

,).

는 k 번째 디스크에 해당하는 집합으로,

≤ 1을 만족하는 (라운드 길이 레벨, 디스크 스피드 레벨)의 쌍을 원소로 갖는 집합이며,

는 의 원소의 개수이고, 각각의 원소는

값에 따라 내림차순으로 정렬될 수 있으며, (

,

)를

의 n 번째 원소라고 한다. 여기서,

은 절감되는 전력을 나타내며, 다음 수학식 5로 정의될 수 있다.here,

Is the set that corresponds to the kth disk,

Is a set having as its elements a pair of (round length level, disc speed level) satisfying ≤ 1,

Is Is the number of elements in each element

Can be sorted in descending order by value, (

,

)

This is called the nth element of. here,

Represents power savings and may be defined by Equation 5 below.

<Equation 5>

FIG. 1 is a diagram illustrating an algorithm for selecting a dynamic round length and a disk rotation speed according to an embodiment of the present invention. As shown in FIG. 1, in the embodiment of the present invention, the sum of disk power consumption is as follows. By minimizing in order, the above round length and speed selection problem (RLSS) can be solved.

와

을 계산하여, 수학식 6과 같이 정의되는

를 구하고 이들의 집합 SG를 구하는 단계;(1) For all disks, it is a parameter about the total energy consumed and the buffer used on the disk.

Wow

Is calculated as

Obtaining a set SG thereof;

<Equation 6>

로 초기화하는 단계; (2) Temporary variable TE

Initializing with;

에서

번째 원소에 해당하는 (

,) 가 라운드 길이 레벨, 디스크 스피드 레벨로 선택된다고 가정하고, 모든

를 1로 초기화하여, 선택된 라운드 길이 레벨

을

로, 선택된 스피드 레벨

을

로 초기화하는 단계;(3) assembly

in

Corresponding to the first element (

Suppose that,) is selected as the round length level, the disk speed level, and all

To 1, the selected round length level

of

, Selected speed level

of

Initializing with;

를 선택하여 SG로부터 제거하는 단계;(4) the element with the largest value in SG

Selecting to remove from SG;

와 총 버퍼 크기 B를 비교하고 h와

를 비교하여, h가

보다 크고

가 B 이하이면, TE는

로,

는

로,

는

로,

는 h로 각각 변환하는 단계;(5)

Compare the total buffer size B with h

By comparing h

Greater than

If is less than or equal to B, TE

in,

Is

in,

Is

in,

Respectively converting to h;

(6) repeating steps (4) to (5) for SG ≠ 0

It may include.

,

)를, 최종 라운드 길이 레벨 및 디스크 회전 속도 레벨로 결정할 수 있다. 예를 들어,

= 2 ,

= 3 으로 결정될 경우, 라운드 레벨의 집합이 {BR, BR + u, BR + 2 * u, BR + 3 * u, BR + 4 * u}이고, 디스크 스피드의 집합이 {7200 rpm, 28800 rpm, 39600 rpm, 72000 rpm}으로 가정할 경우, k 번째 디스크는 39600 rpm 으로 돌리고, k 번째 디스크에서 읽는 비디오 데이터의 라운드 길이는 BR + u 로 적용함으로써, 에너지의 소모를 최소화할 수 있게 된다.Also, the final value obtained after performing the above algorithm (

,

) Can be determined as the final round length level and the disc rotation speed level. E.g,

= 2,

= 3, the set of round levels is {BR, BR + u, BR + 2 * u, BR + 3 * u, BR + 4 * u}, and the set of disk speeds is {7200 rpm, 28800 rpm, Assuming that the k th disk is rotated at 39600 rpm and the round length of the video data read from the k th disk is BR + u, the energy consumption can be minimized.

Experiment result

In order to explain the effects of the proposed invention, simulation experiments were performed. The server used consists of 20 disks, supports up to 61.4 MB / s, and considers commercial Hitachi 7K400 disks with 8.5 ms disk seek time. Assumed support. A linear model was used to model the power dissipated in the disk, and the parameters for the disk are shown in Table 1 below.

TABLE 1

The arrival of the customer request is assumed to follow the Poisson distribution. Further, all 1000 videos are 90 minutes long, have the same bit rate of 1.5 Mb / s, which is the bit rate of MPEG 1, are stored on the disc in a round robin manner, and the access probability follows a Zipf distribution with α = 0.271. The round length set is {1s, 1.3s, 1.6s, 1.9s, 2.2s, 2.5s, 2.8s, 3.1s, 3.4s, 3.7s, 4.0s, 4.3s}. In order to compare the energy savings of the present invention, the present invention is compared with the conventional methods that support a single disk rotational speed and round length with balanced disk utilization and buffer utilization. For fair comparisons, we estimate energy consumption when supporting the same number of customers. For convenience, the method proposed in the present invention is referred to as GSA and the conventional method is referred to as COV.

2 to 4 illustrate relative energy consumption ratios of the GSA scheme according to an embodiment of the present invention with respect to the existing COV scheme according to an inter-arrival time.

As shown in Figures 2 to 4, it can be seen up to 52% energy savings compared to the existing method through the present invention. The longer the internal arrival time, the greater the energy difference, and the greater the energy difference if the COV method supports fast disk rotation speeds. Reducing the disk rotation speed supported by the COV method reduces the energy, but this reduces the disk performance.

One embodiment of the present invention can also be implemented in the form of a recording medium containing instructions executable by a computer, such as a program module executed by the computer. Computer readable media can be any available media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media. In addition, computer readable media may include both computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Communication media typically includes computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave, or other transmission mechanism, and includes any information delivery media.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is shown by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

1 illustrates a dynamic round length, disk rotational speed selection algorithm, in accordance with an embodiment of the present invention.

2 to 4 show the energy consumption ratio in the GSA scheme for the COV scheme that supports a single disk rotation speed, according to the inter-arrival time.

Claims (5)

A disk management method for reducing disk power consumption in a disk array based video server, (a) setting the level (m) of the disk rotation speed and the level (j) of the round length, (b) disk bandwidth utilization for each disk (k) {

} And buffer utilization {

} Calculating, (c) total energy consumption according to the set level (j, m) of each disk k based on the plurality of power modes {

} Calculating, (d) for each disk k, the disk bandwidth utilization {

The first set having as its elements a pair of the round length level (j) and the disk speed level (m), wherein

), (e) The element of the first set includes the calculated total energy consumption {

} Sorting in descending order based on the values, (f) for each aligned element of the first set l, the power savings for the first aligned element {

} Calculating, (g) a value of the rate of change of the power savings relative to the rate of change of buffer utilization for each ordered element of the first set {

} To generate a second set (SG), (h) initializing the temporary variable TE value, (i) in the first set

Selecting an ith element and initializing a round length level (j) and a disk rotational speed level (m) of the selected element, (j) In the second set, the element having the largest value {

} From the second set, (k) the number h of the element with the largest value in the second set, the temporary variable TE, the selected

Based on the buffer utilization at the first element and the buffer utilization at the number h of the element with the largest value in the second set, the temporary variable TE, the selected

The round length level value of the first element and the selected

Changing the disk rotation speed level value of the first element, (l) repeating steps (j) to (k) when the number of elements in the second set is two or more; Disk management method for reducing the disk power consumption comprising a. The method of claim 1, In the step (b), When the buffer size is B, the disk rotation speed level is m, the transfer rate and disk rotation delay time are tr (m) and Td (m), and the disk seek time is disk seek. time) is a constant Ts, the round length at round length level j is Rj, The bit rate of the data of the video stream Vi is dri, the unit is bits / sec, the block size of the disk is bs, one disk has NS disk rotation speed levels, NC disks are arranged, Customers to NC customer groups (

,… ,

After dividing by),

To allow customers within the server to receive streams from the corresponding disk k,

In the video server requesting this video stream Vi, The disk bandwidth utilization

And the buffer utilization

To,

And

To calculate How to manage disks to reduce disk power consumption. delete The method of claim 1, In the step (f), the saving power {

}of

, And (

,

) Is the first set (

Disk management method for reducing disk power consumption. The method of claim 4, wherein In the step (g), A change rate value of the saving power with respect to a change rate of the buffer utilization {

}of

,

With {

Is the first set (

) Is the number of elements}, In the step (h), the temporary variable TE

Initialize to, In the step (k), the number h of the element having the largest value in the second set is the number of the selected element (

Greater than)

Is less than or equal to B, The temporary variable TE

, The round length level of the selected element

The disk rotational speed level of the selected element

The disk management method for reducing the disk power consumption.

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