JP4961275B2 - Storage device and disk device rotation speed control method - Google Patents

Description

  The present invention relates to a technology for reducing power consumption by changing a rotation speed of a disk device in accordance with a request processing status in a storage subsystem, a server, and a disk device.

  In general, storage subsystems and servers are constructed according to the maximum load. In actual system operation, the maximum load is rare, so there are many cases of excessive specification operation, and there is a problem that extra power is consumed.

  In order to solve the above problem, the following three methods have been studied as a method of controlling the disk device in accordance with the operation status of the system. One is a method of saving power by stopping the disk device during the idle period. This method is suitable for applications with low access frequency and long idle time. The second method is a disk device having a low-revolution speed power-saving mode (read / write not possible), and shifts to a low-revolution speed power-saving mode during an idle period to save power. This method is suitable for applications with a relatively high access frequency and a short idle time. The last one consists of a disk device that can perform read / write processing at multiple rotational speeds, monitors the request processing status for the disk device, predicts the excess or deficiency of the disk device performance against the load, and In response to this, the rotational speed of the disk is changed to save power. This method is suitable for applications where the access frequency is high and the load varies greatly.

  For example, in the third power saving method, for each fixed number of requests, an average time for request processing is obtained (hereinafter, referred to as average request processing time), and the obtained average request processing time is set immediately before. There is a method of comparing the average request processing time examined, predicting the excess or deficiency of the performance of the disk device based on the difference from the average request processing time, and changing the rotation speed based on the result. Such rotational speed control is described in Non-Patent Document 1.

S. Gurumurthi, A. Sivasubramaniam, M. Kandemir, H. Franke, “DRPM: dynamic speed control for power management in server class disks”, Annual International Symposium on Computer Architecture, (USA), IEEE Computer Society, 2003, VOL 30 , p.169 181

  In the rotation control of Non-Patent Document 1, although the rotation speed is controlled based on the average request processing time obtained for each predetermined number of requests, the request issuance interval is not taken into account, so the change in request processing status There was a problem that the rotational speed could not be controlled by promptly reflecting the above. For example, when the request issuance interval is very large, or when the request issuance interval varies greatly, it takes time to obtain the average request processing time.

  In view of the above problems, an object of the present invention is to quickly detect a change in the processing status of a request and make it possible to change the rotational speed of the disk device in accordance with the change.

In order to solve the above problems, a storage device of the present invention includes a disk device capable of read / write processing at a plurality of rotational speeds, and
A speed step registration table for registering speed steps that can be set in the disk device, a rotation speed management table for registering the current rotation speed of the disk device, a request processing status monitoring program for monitoring the processing status of requests from the host device, A memory for storing a rotational speed control program for controlling the rotational speed of the disk device according to the processing status of the request;
The request processing status monitoring program is executed to monitor the request processing status within a certain period, the rotational speed control program is executed, and the request processing status monitoring program is registered in the rotational speed management table according to the change in the request processing status. And a control device for controlling the rotation speed of the disk device within a range of speed steps registered in the speed step registration table.

  In order to solve the above-described problem, a disk device rotation speed control method in a storage device according to the present invention includes a step of determining the number of unprocessed requests of a disk device at an arbitrary time and a step of storing the latest request processing end time. A step of counting the number of requests received until a certain period of time elapses from an arbitrary time point, a step of obtaining the number of unprocessed requests at the time of a certain period of time, and the processing status of the request based on the processing of each step And a step of controlling the rotational speed of the disk device in accordance with the detected change in the processing status of the request.

  According to the present invention, a change in the request processing status can be detected quickly, and the rotational speed of the disk device can be changed according to the change, so that the power saving effect can be enhanced.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a functional block diagram showing a schematic configuration of a storage apparatus according to an embodiment of the present invention. The storage device includes a controller unit 101 and a storage unit 103 configured by a group 102 of redundant arrays of inexpensive disks (RAID) configured by a plurality of disk devices. The controller unit 101 controls the rotation speed of the disk devices constituting the RAID group 102. The RAID group 102 represents a physical control unit. The controller unit 101 includes a rotation speed management table 104, a request processing status monitoring unit 105, a rotation speed control unit 106, and a speed step registration table 107.

  FIG. 1B shows a hardware configuration for realizing the functions shown in FIG. 1A. The request processing status monitoring unit 105 and the rotation speed control unit 106 are microprograms, and these microprograms are stored in the memory 110 together with the rotation speed management table 104 and the speed step registration table 107, and are configured by a microprocessor or the like. This is executed by the control device 120.

  FIG. 2 shows a configuration example of the RAID group 102. The RAID group 102 includes a plurality of magnetic disk devices (HDD) 21. In the storage apparatus of this embodiment, the HDD 21 is configured with an HDD that can perform read / write processing at a plurality of rotational speeds. The RAID group 102 is composed of one or more logical units (LUs) 22. In the example of FIG. 2, the RAID group 102 is composed of two LUs 22.

  FIG. 3 shows an example of the configuration of the LU 31 when configured with RAID5. In the case of RAID5, the physical space on the disk is composed of data units called stripes 32. The LU 31 is configured by sequentially arranging the stripes in the RAID group 102. The stripe 32 records not only data to be stored but also data 33 for restoring data when the HDD fails (this data is referred to as parity data). In FIG. 3, stripes 32 in which numerical values are described indicate stored data, and “P” indicates parity data.

  FIG. 4 shows an example of setting the rotational speed of the disk device 21 that can perform read / write processing at a plurality of rotational speeds. When processing the request, the disk device 21 selects and executes one of the rotational speeds. Further, the storage apparatus registers the rotational speed at which the request processing is actually executed among the rotational speeds shown in FIG. 4 in the rotational speed management table 104 of FIG. The speed steps that can be set by the disk device 21 are registered in advance in the speed step registration table 107 when the system is constructed. The example of FIG. 4 shows an example in which five rotation speeds are set every 2500 rpm with 2500 rpm as the lower limit. When the request processing status monitoring unit 105 checks the request processing status and the rotational speed control unit 106 obtains the rotational speed according to the status, the storage device changes the rotational speed of each disk device 21 constituting the RAID group 102. To do.

FIG. 5 shows a flowchart of processing of the request processing status monitoring unit. The request processing status monitoring unit 105 obtains the number of unprocessed requests in Time (A) (step 501). Next, the latest request processing end time is stored (step 502). Next, the number of requests received until a certain period ΔT elapses from Time (A) is counted (step 503). Next, the number of unprocessed requests at Time (A + ΔT) is obtained (step 504). If there is no unprocessed request count in Time (A + ΔT) (step 505), the free time of the disk device is obtained (step 506). The free time can be obtained by subtracting the latest request processing end time from Time (A + ΔT). Next, a ratio of free time to ΔT (hereinafter referred to as a ratio of free time) is obtained (step 507) .The ratio of free time can be obtained by the following equation.
Free time ratio = Free time / ΔT
Returning to step 505, if there is the number of unprocessed requests in Time (A + ΔT), the undigested rate of requests is obtained (step 508). The undigested rate of the request can be obtained by the following formula.
Unsettled rate of requests = number of unprocessed requests at Time (A + ΔT) / (number of unprocessed requests at Time (A) + total number of requests received during ΔT)
The rotational speed control unit (106) determines the rotational speed of the disk device 21 based on the percentage of free time or the request undigested rate obtained above. In the storage device of this embodiment, the request processing status is monitored for each RAID group 102.

  FIG. 6 shows a flowchart of a process for reducing the rotation speed according to the percentage of idle time. The storage device according to the present embodiment checks whether the percentage of free time is greater than 5% and less than 25% (step 601), and if greater than 5% and less than 25%, the rotation speed is set to the current rotation. Decrease by one step from the speed (step 602). Returning to step 601, if the free time breakage is greater than 5% and not less than 25%, it is further checked whether the free time ratio is greater than 25% and less than 50% (step 603). If it is greater than 25% and less than 50%, the rotational speed is lowered by two steps from the current rotational speed (step 604). Returning to step 603, if the percentage of free time is greater than 25% and not less than 50%, it is further checked whether the percentage of free time is greater than 50% and less than 75% (step 605). As a result, if it is greater than 50% and less than 75%, the rotational speed is lowered by three steps from the current rotational speed (step 606). Returning to step 605, if it is greater than 50% and not less than 75%, it is checked whether the ratio of free time> 75% (step 607). If the ratio of idle time> 75%, the current rotational speed is lowered by four steps (step 608). Returning to step 607, if the percentage of idle time is not> 75%, the current rotational speed is maintained.

  FIG. 11 shows a flowchart of a process for obtaining the rotational speed to be changed based on the relative speed step number obtained by the process of FIG. The storage device obtains the current rotation speed of the RAID group 102 to be processed from the rotation speed management table 104 (step 1101). Next, referring to the speed step registration table 107, the rotational speed at the relative speed stage obtained by the processing of FIG. 6 is obtained from the current rotational speed (step 1102). If the obtained relative speed stage is within the registration range of the speed step registration table 107 (step 1103), the rotation speed is changed to the obtained rotation speed (step 1104). Returning to step 1103, if it is not within the registration range of the speed step registration table 107, it is changed to the minimum rotation speed of the registration range (step 1105).

  For example, in a disk device having a rotational speed as shown in FIG. 4, if the current rotational speed is 7500 rpm, the rotational speed that can be lowered from 7500 rpm is 2 even if the result determined by the rotational speed control unit is three steps lower. Since it is under the stage, change the rotation speed to 2500rpm. When the rotation speed is changed, the changed rotation speed is re-registered in the rotation speed management table 104.

  FIG. 7 shows an example in which the two-stage rotational speed is lowered from the current rotational speed. When the disk device 21 constituting the storage device has the five-stage rotation speed shown in FIG. 4, the current rotation speed 71 is 10,000 rpm, and when the rotation speed is lowered by two stages from the rotation speed, 5000 rpm. The rotation speed is changed to (72). The current rotation speed 71 can be checked using the rotation speed management table 104.

  FIG. 8 shows a flowchart of processing for increasing the rotation speed in accordance with the unprocessed status of the request. The storage device checks whether the request undigested rate is greater than 5% and less than 25% (step 801). If the request rate is greater than 5% and less than 25%, the rotation speed is increased by one step from the current rotation speed. (Step 802). Returning to step 801, if it is greater than 5% and not less than 25%, it is checked whether the request undigested rate is greater than 25% and less than 50% (step 803). In the following cases, the rotational speed is increased by two stages from the current rotational speed (step 804). Returning to step 803, if the request undigested rate is greater than 25% and not less than 50%, it is checked whether the request undigested rate is greater than 50% and less than 75% (step 805). If the request undigested rate is greater than 50% and less than 75%, the rotational speed is increased by three levels from the current rotational speed (step 806). Returning to step 805, if the request undigested rate is greater than 50% and not less than 75%, it is checked whether the request undigested rate> 75% (step 807). As a result, if the request undigested rate is greater than 75%, the rotational speed is increased by four stages from the current stage (step 808). In step 807, if the request undigested rate is not> 75%, the current rotation speed is maintained.

  FIG. 12 shows a flowchart of a process for obtaining the rotational speed to be changed based on the relative speed step number obtained by the process of FIG. The storage device obtains the current rotation speed of the RAID group 102 to be processed from the rotation speed management table 104 (step 1201). Next, with reference to the speed step registration table 107, the rotational speed at the relative speed stage obtained by the processing of FIG. 8 is obtained from the current rotational speed (step 1202). If the obtained relative speed stage is within the registration range of the speed step registration table 107 (step 1203), it is changed to the obtained rotation speed (step 1204). Returning to step 1203, if it is not within the registration range of the speed step registration table 107, it is changed to the maximum rotation speed of the registration range (step 1205).

  For example, in a disk device having a rotational speed as shown in FIG. 4, if the current rotational speed is 7500 rpm, the rotational speed that can be increased from 7500 rpm is 2 even if the result set by the rotational speed control unit is three stages higher. Since it is up to the stage, the rotation speed is changed to 12500 rpm. When the rotation speed is changed, the changed rotation speed is re-registered in the rotation speed management table 104.

  FIG. 9 shows an example in which the two-stage rotational speed is increased from the current rotational speed. When the disk device constituting the storage device has the five-stage rotation speed shown in FIG. 4, assuming that the current rotation speed 91 is 5000 rpm, the rotation speed is increased to 10,000 rpm (92) when the two-stage rotation speed is increased. Will be changed. The current rotation speed 91 can be checked using the rotation speed management table 104.

  It is desirable to implement the method for changing the rotation speed for each RAID group 102. When the storage device is composed of a plurality of RAID groups 102, the rotation speed is controlled for each RAID group 102.

FIG. 10 shows a flowchart of processing for controlling the timing of monitoring the request processing status. Immediately after the rotation speed is changed, the request is likely to be delayed due to the shift. Therefore, after the rotation speed is changed, monitoring of the request processing status is started after the processing is stabilized.
The storage apparatus of this embodiment checks whether T seconds have elapsed after changing the rotational speed of the disk device (step 1001), and starts monitoring request processing status when T seconds have elapsed (process 1002). Returning to step 1001, if T seconds have not elapsed, the process returns to the beginning.

  As described above, according to the embodiment of the present invention, it is possible to quickly change the rotation speed of the disk device according to the request processing status by monitoring the request processing status at regular intervals. The power saving effect of the storage device can be enhanced. This is particularly effective for applications where the request issuance interval varies.

It is a functional block diagram of a storage apparatus according to an embodiment of the present invention. It is a hardware block diagram of the storage apparatus by the Example of this invention. It is a figure which shows the structural example of a RAID group. It is a figure which shows the example of the data format in a RAID group. It is a figure which shows the example of a setting of the rotational speed of a disc apparatus. It is a flowchart which shows the process of a request process condition monitoring part. It is a flowchart which shows the process which calculates | requires the relative speed step in the case of reducing a rotational speed. It is a figure which shows the example of the speed change operation | movement in the case of reducing a rotational speed. It is a flowchart which shows the process which calculates | requires the relative speed step in the case of raising a rotational speed. It is a figure which shows the example of the speed change operation | movement when raising a rotational speed. It is a flowchart which controls the start timing of a request processing condition monitoring process. It is a flowchart which shows the process in the case of reducing a rotational speed. It is a flowchart which shows the process in the case of raising a rotational speed.

Explanation of symbols

21: Disk device,
22 ... LU (Logical Unit),
31 ... LU,
32 ... stripes,
33 ... parity data,
71, 91 ... Current rotation speed,
72, 92 ... rotation speed after change,
101 ... Controller part,
102 ... RAID group,
103 ... storage unit,
104: Rotational speed management table,
105 ... request processing status monitoring unit (program),
106: Rotational speed control unit (program),
107 ... speed step registration table,
110: Memory,
120... Control device.

Claims (10)

A disk device capable of read / write processing at multiple rotational speeds;
A first table for registering speed steps that can be set in the disk device, a second table for registering the current rotational speed of the disk device, and a first program for monitoring the processing status of requests from the host device And a memory for storing a second program for controlling the rotational speed of the disk device according to the processing status of the request;
Execute the first program to monitor the processing status of requests within a certain period, and execute the second program according to the number of unprocessed requests in the total number of requests within a certain period. Alternatively, the rotational speed of the disk device registered in the second table is registered in the first table according to the ratio of the period during which no processing is performed in the disk device within the coincidence period. And a control device for controlling within a range of speed steps.   The control device calculates a ratio of the number of unprocessed requests to the total number of requests within a certain period when an unprocessed request remains after a certain period of time when executing the first program, and this ratio 2. The storage apparatus according to claim 1, wherein control is performed so as to increase the rotational speed of the disk device in response to the request.   When the rotational speed of the disk device is increased, the current speed of the disk device is obtained from the second table, and the number of speed steps corresponding to the ratio from the current speed is obtained by referring to the first table. 3. The storage apparatus according to claim 2, wherein the change is made by the number of speed steps obtained.   In the execution of the first program, when there is no unprocessed request remaining after the lapse of a certain period, the control apparatus obtains a period during which the disk apparatus is not performing processing within a certain period, and performs this process. 2. The storage apparatus according to claim 1, wherein a ratio of an unoccupied period to the fixed period is calculated, and control is performed so as to reduce the rotational speed of the disk apparatus according to the ratio.   When the rotational speed of the disk device is lowered, the current speed of the disk device is obtained from the second table, and the number of speed steps corresponding to the ratio from the current speed is obtained by referring to the first table. 5. The storage apparatus according to claim 4, wherein the change is made by the number of speed steps obtained.   6. The storage apparatus according to claim 3, wherein the changed rotation speed is registered in the second table.   5. The storage apparatus according to claim 2, wherein monitoring of the request processing status is started after a predetermined time has elapsed after the rotation speed is changed. Determining the number of outstanding requests for the disk device at an arbitrary time;
Storing the latest request processing end time;
Counting the number of requests received from the arbitrary point in time until a certain period of time elapses;
Obtaining the number of unprocessed requests at the time of the predetermined period;
Detecting a change in the processing status of the request based on the processing of each step;
The disk device according to the number of unprocessed requests in the total number of requests within a certain period detected in the step or according to the ratio of the period during which no processing is performed in the disk device within the matching period And a method of controlling the rotational speed of the disk device in the storage device.   When unprocessed requests remain after the lapse of the predetermined period, the ratio of the number of unprocessed requests to the total number of requests within the predetermined period is calculated, and the rotational speed of the disk device is increased according to this ratio. 9. The method of controlling a rotational speed of a disk device in a storage device according to claim 8.   When there is no number of unprocessed requests at the time when the fixed period has elapsed, the free time of the disk device is obtained by subtracting the latest request processing end time from the time at which the fixed period has elapsed, and the fixed period of the free time 9. The method for controlling the rotational speed of a disk device in a storage apparatus according to claim 8, wherein the ratio of the disk device is calculated, and the rotational speed of the disk device is lowered according to the ratio.

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