Patent Publication Number: US-11665228-B2

Title: Management device, storage system, and information processing method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2021-95239, filed on Jun. 7, 2021, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiment discussed herein is related to a management device, a storage system, and an information processing method. 
     BACKGROUND 
     A cluster system that has a storage via a network exists. 
     In the cluster system, a plurality of servers is prepared as a cluster connected with the network and applications share and use its hardware. As one form of a cluster configuration, there is a system in which a computational resource (CPU) is separated from a storage resource (storage). As an application execution form, low overhead containers have been adopted. 
     US Patent Publication No. 2018/0248949, US Patent Publication No. 2019/0306022, and Japanese National Publication of International Patent Application No. 2016-528617 are disclosed as related art. 
     SUMMARY 
     According to an aspect of the embodiments, an apparatus includes . . . A management device of a storage system, the management devices includes: a memory; and a processor coupled to the memory and configured to: acquire workload load information and system load information when executing a container, and determine a workload arrangement destination and a replica position of a volume based on the workload load information and the system load information when activating a workload. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a diagram for explaining an example of reading data in a cluster system; 
         FIG.  2    is a block diagram for briefly explaining acquisition and accumulation of workload load information according to an embodiment; 
         FIG.  3    is a block diagram for explaining a replica position determination operation in a storage system as the embodiment; 
         FIG.  4    is a block diagram schematically illustrating a structure example of the storage system illustrated in  FIG.  3   ; 
         FIG.  5    is a block diagram schematically illustrating a hardware structure example of an information processing device as the embodiment; 
         FIG.  6    is a block diagram schematically illustrating a software structure example of a management node illustrated in  FIG.  3   ; 
         FIG.  7    is a block diagram schematically illustrating a software structure example of a compute node illustrated in  FIG.  3   ; 
         FIG.  8    is a block diagram schematically illustrating a software structure example of a storage node illustrated in  FIG.  3   ; 
         FIG.  9    is a flowchart for explaining replica position determination processing according to the embodiment; 
         FIG.  10    is a flowchart for explaining details of processing for arranging a CPU and an accelerator illustrated in  FIG.  9   ; 
         FIG.  11    is a flowchart for explaining details of processing for arranging a storage illustrated in  FIG.  9   ; 
         FIG.  12    is a table for explaining a band target value in the processing for arranging the storage illustrated in  FIG.  11   ; and 
         FIG.  13    is a flowchart for explaining storage node rebalance processing according to the embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     US Patent Publication No. 2018/0248949, US Patent Publication No. 2019/0306022, and Japanese National Publication of International Patent Application No. 2016-528617 are disclosed as related art. 
       FIG.  1    is a diagram for explaining an example of reading data in a cluster system. 
     In the cluster system illustrated in  FIG.  1   , for each of data A and B stored in a storage #1 and data C stored in a storage #2, data A′ as a replica is stored in the storage #2, and data B′ and data C′ as replicas are stored in a storage #3. 
     As indicated by a reference A 1 , a server #1 reads the data A from the storage #1. Furthermore, as indicated by a reference A 2 , a server #2 reads the data B from the storage #1. Moreover, as indicated by a reference A 3 , a server #3 reads the data C from the storage #2. 
     In this way, in a case where a workload is not controlled in the cluster system, the workloads are concentrated on a specific storage (storage #1 in the example illustrated in  FIG.  1   ), and there is a possibility that throughput decreases. 
     In one aspect, an object is to distribute loads in a storage system so as to improve throughput. 
     [A] Embodiment 
     Hereinafter, an embodiment will be described with reference to the drawings. Note that the embodiment to be described below is merely an example, and there is no intention to exclude application of various modifications and techniques not explicitly described in the embodiment. In other words, for example, the present embodiment may be variously modified and implemented without departing from the scope of the gist thereof. Furthermore, each drawing is not intended to include only components illustrated in the drawings and may include another function and the like. 
     Hereinafter, each same reference code represents a similar part in the drawings, and thus description thereof will be omitted. 
     [A-1] Structure Example 
       FIG.  2    is a block diagram for briefly explaining acquisition and accumulation of workload load information according to the embodiment. 
     When a workload is executed, workload load information  131  is acquired and is saved in association with a workload ID. In other words, when a container is executed, a status of an access to a resource is acquired. Then, resource request information is accumulated in association with a container image. 
     As loads when the workload is executed, a CPU load, a memory load, a used volume and an accelerator load of a graphics processing unit (GPU) or the like, and an input/output (I/O) load are observed. The I/O load may be an average, a maximum value, or a variance of a total amount of data or a speed. 
     The I/O load may be acquired as being classified into an I/O load between a CPU  101  and a storage  103 , an I/O load between the CPU  101  and a network  102 , an I/O load between the CPU  101  and an accelerator  104 , and an I/O load between the accelerator  104  and the storage  103 . 
     The CPU  101  and the accelerator  104  may built a memory therein. 
       FIG.  3    is a block diagram for explaining a replica position determination operation in a storage system  100  as the embodiment. 
     The storage system  100  includes a management node  1 , a plurality of (three in the illustrated example) compute nodes  2 , and a plurality of (three in the illustrated example) storage nodes  3 . 
     The management node  1  is an example of a management device. Upon receiving a workload execution request, the management node  1  collects the workload load information  131 , node resource information  132 , compute node load information  133 , accelerator load information  134 , storage node load information  135 , and volume arrangement information  136 . Then, the management node  1  schedules a workload (WL)  210  and an accelerator (ACC)  220  and determines arrangement of the workload  210  and a replica position of a used volume. 
     The workload load information  131  indicates a load caused by the workload  210  executed by the compute node  2 . 
     The node resource information  132  is static information indicating how much the memories, the CPUs, the accelerators  220 , or the like each node includes. 
     The compute node load information  133  indicates loads of a CPU, a memory (MEM), and a network (NET) in the compute node  2 . 
     The accelerator load information  134  indicates a load of the accelerator  220  in the compute node  2 . 
     The storage node load information  135  indicates a load of a disk  13  in the storage node  3 . 
     The volume arrangement information  136  indicates which volume exists in each storage node  3 . 
     In the management node  1 , a scheduler  110  to be described later with reference to  FIG.  4    grasps a resource usage status. At the time when the workload  210  (in other words, container) is activated, the compute node  2  (in other words, CPU node and accelerator node) and the storage node  3  are determined based on a load request and the resource usage status of the workload  210 . The determination is made considering that increase in the I/O load does not exceed a network slack (in other words, margin) of an arrangement node, the selection of the storage node  3  is dynamically controlled according to a load status. 
       FIG.  4    is a block diagram schematically illustrating a structure example of the storage system  100  illustrated in  FIG.  3   . 
     The storage system  100  is, for example, a cluster system and includes the management node  1 , the plurality of (two in the example illustrated in  FIG.  4   ) compute nodes  2 , and the plurality of (two in the example illustrated in  FIG.  4   ) storage nodes  3 . The management node  1 , the plurality of compute nodes  2 , and the plurality of storage nodes  3  are connected via a network  170 . 
     The management node  1  is an example of a management device and includes the scheduler  110 , information  130 , and a network interface card (NIC)  17 . The scheduler  110  determines arrangement of the workload  210  in the compute node  2  and the disk  13  in the storage node  3 . The information  130  includes the workload load information  131 , the node resource information  132 , the compute node load information  133 , the accelerator load information  134 , the storage node load information  135 , and the volume arrangement information  136  illustrated in  FIG.  3   . The NIC  17  connects the management node  1  to the network  170 . 
     Each compute node  2  is an example of a server device and includes a plurality of (three in the example illustrated in  FIG.  4   ) workloads  210  and the NIC  17 . The workload  210  is arranged by the management node  1  and is executed to access data of the storage node  3 . The NIC  17  connects the compute node  2  to the network  170 . 
     Each storage node  3  is an example of a storage device and includes a plurality of (three in the example illustrated in  FIG.  4   ) disks  13  and the NIC  17 . The disk  13  is a storage device that stores data to be accessed from the compute node  2 . The NIC  17  connects the storage node  3  to the network  170 . 
       FIG.  5    is a block diagram schematically illustrating a hardware structure example of an information processing device  10  as the embodiment. 
     The hardware structure example of the information processing device  10  illustrated in  FIG.  5    indicates a hardware configuration example of each of the management node  1 , the compute node  2 , and the storage node  3  illustrated in  FIG.  4   . 
     The information processing device  10  includes a processor  11 , a random access memory (RAM)  12 , the disk  13 , a graphic interface (I/F)  14 , an input I/F  15 , a storage I/F  16 , and a network I/F  17 . 
     The processor  11  is, for example, a processing device that performs various controls and calculations, and implements various functions by executing an operating system (OS) and programs stored in the RAM  12 . 
     Note that, the program that implements the functions as the processor  11  may be provided in a form recorded in a computer-readable recording medium, for example, a flexible disk, a compact disc (CD) (CD-read only memory (ROM), CD-recordable (R), CD-rewritable (RW), or the like), a digital versatile disc (DVD) (DVD-ROM, DVD-RAM, DVD-R, DVD+R, DVD-RW, DVD+RW, high definition (HD) DVD, or the like), a Blu-ray disc, a magnetic disc, an optical disc, a magneto-optical disc, or the like. Then, a computer (the processor  11  in the present embodiment) may read the program from the recording medium described above via a reading device (not illustrated), transfer and store the read program in an internal recording device or an external recording device, and use the program. Furthermore, the program may also be recorded in a storage device (recording medium), for example, a magnetic disc, an optical disc, a magneto-optical disc, or the like, and may also be provided to the computer from the storage device via a communication path. 
     When the functions as the processor  11  are implemented, the programs stored in the internal storage device (the RAM  12  in the present embodiment) can be executed by the computer (the processor  11  in the present embodiment). Furthermore, the computer may also read and execute the program recorded in the recording medium. 
     The processor  11  controls the entire information processing device  10 . The processor  11  may also be a multiprocessor. The processor  11  may also be, for example, any one of a central processing unit (CPU), a micro processing unit (MPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), and a field programmable gate array (FPGA). Furthermore, the processor  11  may also be a combination of two or more types of elements of the CPU, MPU, DSP, ASIC, PLD, and FPGA. 
     The RAM  12  may be, for example, a dynamic RAM (DRAM). A software program of the RAM  12  may be appropriately read and executed by the processor  11 . Furthermore, the RAM  12  may be used as a primary recording memory or a working memory. 
     The disk  13  is, for example, a device that stores data in a readable and writable manner, and, for example, a hard disk drive (HDD), a solid state drive (SSD), and a storage class memory (SCM) may be used. 
     The graphic I/F  14  outputs a video to a display device  140 . The display device  140  is a liquid crystal display, an organic light-emitting diode (OLED) display, a cathode ray tube (CRT), an electronic paper display, or the like, and displays various types of information for an operator or the like. 
     The input I/F  15  receives an input of data from an input device  150 . The input device  150  is, for example, a mouse, a trackball, and a keyboard, and the operator performs various input operations via the input device  150 . The input device  150  and the display device  140  may also be combined and may also be, for example, a touch panel. 
     The storage I/F  16  inputs and outputs data to a medium reader  160 . The medium reader  160  is configured so that a recording medium can be attached thereto. The medium reader  160  is configured to be able to read information recorded in the recording medium in a state where the recording medium is attached. In this example, the recording medium is portable. For example, the recording medium is a flexible disc, an optical disc, a magnetic disc, a magneto-optical disc, a semiconductor memory, or the like. 
     The network I/F  17  is an interface device that connects the information processing device  10  to the network  170  and communicates with another information processing device  10  (in other words, management node  1 , compute node  2 , or storage node  3 ) and an external device (not illustrated) via the network  170 . As the network I/F  17 , various interface cards complying with the standards of the network  170 , for example, a wired local area network (LAN), a wireless LAN, a wireless wide area network (WWAN) can be used. 
       FIG.  6    is a block diagram schematically illustrating a software structure example of the management node  1  illustrated in  FIG.  3   . 
     The management node  1  functions as the scheduler  110  and an information exchange unit  111 . 
     The information exchange unit  111  acquires the workload load information  131 , the compute node load information  133 , the storage node load information  135 , and the accelerator load information  134  from another node (in other words, compute node  2  and storage node  3 ) via the network  170 . 
     In other words, when executing the container, the information exchange unit  111  acquires the workload load information  131  and system load information (in other words, compute node load information  133 , accelerator load information  134 , and storage node load information  135 ). 
     The scheduler  110  determines the arrangement of the workload  210  on the basis of the workload load information  131 , the compute node load information  133 , the storage node load information  135 , and the accelerator load information  134  acquired by the information exchange unit  111 , in addition to the node resource information  132  and the volume arrangement information  136 . 
     In other words, when the workload  210  is activated, the scheduler  110  determines an arrangement destination of the workload  210  and the replica position of the volume on the basis of the workload load information  131  and the system load information. 
     The scheduler  110  may select a first compute node  2  of which a sum of a communication amount between the processor  11  and the network  170 , a communication amount between the processor  11  and the volume, and a communication amount between the accelerator  220  and the volume is equal to or less than a margin in the network  170  from among the plurality of compute nodes  2 . Furthermore, the scheduler  110  may select a second compute node  2  of which a sum of the communication amount between the processor  11  and the network  170 , the communication amount between the processor  11  and the volume, and a communication amount between the processor  11  and the accelerator  220  is equal to or less than the margin in the network  170  from among the plurality of compute nodes  2 . Then, the scheduler  110  may determine the first compute node  2  or the second compute node  2  as the arrangement destination of the workload  210 . 
     The scheduler  110  may select one or more first storage nodes  3  of which a sum of the communication amount between the processor  11  and the volume and the communication amount between the accelerator  220  and the volume is equal to or less than the margin in the network  170  from among the plurality of storage nodes  3 . Then, the scheduler  110  may determine the one or more first storage nodes  3  as the replica positions. 
     In a case where a difference between the loads of the plurality of storage nodes  3  included in the storage system  100  exceeds a threshold, the scheduler  110  may also determine the replica position. 
       FIG.  7    is a block diagram schematically illustrating a software structure example of the compute node  2  illustrated in  FIG.  3   . 
     The compute node  2  includes a workload deployment unit  211 , an information exchange unit  212 , and a load information acquisition unit  213  as an agent. 
     The load information acquisition unit  213  acquires load information  230  including the workload load information  131 , the compute node load information  133 , and the accelerator load information  134  illustrated in  FIG.  6    from an OS  20 . 
     The information exchange unit  212  transmits the load information  230  acquired by the load information acquisition unit  213  to the management node  1  via a virtual switch (VSW)  214  and the network  170 . 
     The workload deployment unit  211  deploys the workload (WL)  210  based on the determination by the management node  1 . 
       FIG.  8    is a block diagram schematically illustrating a software structure example of the storage node  3  illustrated in  FIG.  3   . 
     The storage node  3  includes an information exchange unit  311  and a load information acquisition unit  312  as an agent. 
     The load information acquisition unit  312  acquires load information  330  including the storage node load information  135  illustrated in  FIG.  6    from an OS  30 . 
     The information exchange unit  311  transmits the load information  330  acquired by the load information acquisition unit  312  to the management node  1  via a VSW  313  and the network  170 . 
     [A-2] Exemplary Operation 
     The processing for determining the replica position according to the embodiment will be described with reference to the flowchart (steps S 1  to S 5 ) illustrated in  FIG.  9   . 
     The management node  1  arranges the CPU and the accelerator  220  (step S 1 ). Note that details of the processing for arranging the CPU and the accelerator  220  will be described later with reference to  FIG.  10   . 
     The management node  1  determines whether or not the CPU and the accelerator  220  can be arranged (step S 2 ). 
     When it is not possible to perform the arrangement (refer to NO route in step S 2 ), the procedure proceeds to step S 5 . 
     On the other hand, when it is possible to perform the arrangement (refer to YES route in step S 2 ), the management node  1  arranges the storage (step S 3 ). Note that, the processing for arranging the storage will be described later with reference to  FIG.  11   . 
     The management node  1  determines whether or not the storage can be arranged (step S 4 ). 
     When it is not possible to perform the arrangement (refer to NO route in step S 4 ), the management node  1  makes the workload  210  be in a standby state (step S 5 ). Then, the processing for determining the replica position ends. 
     On the other hand, when it is possible to perform the arrangement (refer to YES route in step S 4 ), the processing for determining the replica position ends. 
     Next, the details of the processing for arranging the CPU and the accelerator  220  illustrated in  FIG.  9    will be described with reference to the flowchart (steps S 11  to S 17 ) illustrated in  FIG.  10   . 
     The management node  1  sets a set of nodes that satisfy requirements of the CPU and the memory (MEM) as X, a set of nodes that satisfy requirements of the accelerator (ACC)  220  as Y, and a product set X n Y of X and Y as Z (step S 11 ). 
     The management node  1  selects one node that satisfies a network requirement “CPU_NET+CPU_VOL+ACC_VOL&lt;=network slack” from among the set Z (step S 12 ). Note that, CPU_NET indicates a communication amount between the CPU and the network, CPU_VOL indicates a communication amount between the CPU and the volume, and ACC_VOL indicates a communication amount between the accelerator  220  and the volume. Furthermore, the network slack indicates a margin of a network amount of one node. 
     The management node  1  determines whether or not a node that satisfies the network requirement has been found (step S 13 ). 
     When the node that satisfies the network requirement has been found (refer to YES route in step S 13 ), it is considered that it is possible to perform the arrangement, and the processing for arranging the CPU and the accelerator  220  ends. 
     On the other hand, when the node that satisfies the network requirement has not been found (refer to NO route in step S 13 ), the management node  1  selects one node that satisfies a network requirement “CPU_NET+CPU_VOL+CPU_ACC&lt;=network slack” from among the set X (step S 14 ). Note that CPU—NET indicates a communication amount between the CPU and the network, CPU_VOL indicates a communication amount between the CPU and the volume, and CPU_ACC indicates a communication amount between the CPU and the accelerator  220 . Furthermore, the network slack indicates a margin of a network amount of one node. 
     The management node  1  determines whether or not a node that satisfies the network requirement has been found (step S 15 ). 
     When the node that satisfies the network requirement has not been found (refer to NO route in step S 15 ), it is considered that it is not possible to perform the arrangement, and the processing for arranging the CPU and the accelerator  220  ends. 
     On the other hand, when the node that satisfies the network requirement has been found (refer to YES route in step S 15 ), the management node  1  selects one node that satisfies a network requirement “ACC_VOL+CPU_ACC&lt;=network slack” from among the set Y (step S 16 ). Note that, ACC_VOL indicates a communication amount between the accelerator  220  and the volume, and CPU_ACC indicates a communication amount between the CPU and the accelerator  220 . Furthermore, the network slack indicates a margin of a network amount of one node. 
     The management node  1  determines whether or not a node that satisfies the network requirement has been found (step S 17 ). 
     When the node that satisfies the network requirement has been found (refer to YES route in step S 17 ), it is considered that it is possible to perform the arrangement, and the processing for arranging the CPU and the accelerator  220  ends. 
     On the other hand, when the node that satisfies the network requirement has not been found (refer to NO route in step S 17 ), it is considered that it is not possible to perform the arrangement, and the processing for arranging the CPU and the accelerator  220  ends. 
     Next, the details of the processing for arranging the storage illustrated in  FIG.  9    will be described with reference to the flowchart (steps S 21  to S 26 ) illustrated in  FIG.  11   . 
     The management node  1  sets a set of the storage nodes  3  each having the replica of the volume as V (step S 21 ). 
     The management node  1  selects one node that satisfies a network requirement “CPU_VOL+ACC_VOL&lt;=network slack” from among the set V (step S 22 ). Note that, CPU_VOL indicates a communication amount between the CPU and the volume, and ACC_VOL indicates a communication amount between the accelerator  220  and the volume. Furthermore, the network slack indicates a margin of a network amount of one node. 
     The management node  1  determines where or not a node that satisfies the network requirement has been found (step S 23 ). 
     When the node that satisfies the network requirement has been found (refer to YES route in step S 23 ), it is considered that it is possible to perform the arrangement, and the processing for arranging the storage ends. 
     On the other hand, when the node that satisfies the network requirement has not been found (refer to NO route in step S 23 ), the management node  1  selects a plurality of nodes that satisfies a network requirement “CPU_VOL+ACC_VOL&lt;=network slack” in combination from among the set V (step S 24 ). Note that, CPU_VOL indicates a communication amount between the CPU and the volume, and ACC_VOL indicates a communication amount between the accelerator  220  and the volume. Furthermore, the network slack indicates a margin of a network amount of one node. 
     The management node  1  arranges the volume in the selected node (step S 25 ). 
     The management node  1  determines whether or not a node that satisfies the network requirement has been found (step S 26 ). 
     When the node that satisfies the network requirement has been found (refer to YES route in step S 26 ), it is considered that it is possible to perform the arrangement, and the processing for arranging the storage ends. 
     On the other hand, when the node that satisfies the network requirement has not been found (refer to NO route in step S 26 ), it is considered that it is not possible to perform the arrangement, the processing for arranging the storage ends. 
       FIG.  12    is a table for explaining a band target value in the processing for arranging the storage illustrated in  FIG.  11   . 
     It is assumed that there be three used volumes V 1 , V 2 , and V 3  and a replica is included in the storage node  3 . In the example illustrated in  FIG.  12   , replicas of the volume V 1  are arranged in storage nodes #1 and #2, replicas of the volume V 2  are arranged in storage nodes #2 and #3, and replicas of the volume V 3  are arranged in storage nodes #1 and #3. Furthermore, loads of the respective volumes V 1 , V 2 , and V 3  are set as R 1 , R 2 , and R 3 , respectively. 
     Network slacks of the respective storage nodes  3  are set as S 1 , S 2 , and S 3 . 
     The storages are allocated according to a procedure including the following procedures (1) to (4). 
     (1) R 11  and R 31  are allocated as much as possible within a range that does not exceed S 1 . At this time, priority is given to R 11 . Note that, R 11 =min (S 1 , R 1 ) and R 31 =min (S 1 −R 11 , R 3 ).
 
 R   11   +R   31   ≤S   1   ,R   11   ≤R   1   , R   31   ≤R   3  
 
     (2) R 12  and R 22  are allocated as much as possible within a range that does not exceed S 2 . At this time, priority is given to R 12 .
 
 R   12   +R   21   ≤R   2   ,R   12   =R   1   −R   11   ,R   22   ≤R   2  
 
     (3) R 23  and R 33  are allocated within a range that does not exceed S 3 .
 
 R   23   +R   33   ≤S   3   ,R   23   =R   2   −R   22   ,R   33   =R   3   −R   31  
 
     (4) When (1) to (3) described above are not satisfied, it is not possible to perform allocation. 
     Then, access to the volume is controlled so as to satisfy the band target value. In a case where the volume of the storage node  3  includes N blocks, an access band R to each block is distributed to R 1  and R 2  (R=R 1 +R 2 ). 
     When the workload  210  is deployed, the number of blocks corresponding to two nodes of the replicas of the volume is divided into N1 and N2 as follows. 
     
       
         
           
             
               
                 
                   
                     
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     Furthermore, at the time when the workload  210  is executed, an execution node of the workload  210  that accesses the volume limits an access band to the volume to R. In a status where accesses to the respective blocks are uniformly performed, access bands to the respective replicas are R 1  and R 2 . 
     Next, processing for rebalancing the storage nodes  3  in the embodiment will be described with reference to the flowchart (steps S 31  and S 32 ) illustrated in  FIG.  13   . 
     The management node  1  determines whether or not a difference between the loads of the respective storage nodes  3  exceeds a threshold at regular intervals (step S 31 ). 
     When the difference between the loads of the respective storage nodes  3  does not exceed the threshold (refer to NO route in step S 31 ), the processing in step S 31  is repeatedly executed. 
     On the other hand, when the difference between the loads of the respective storage nodes  3  exceeds the threshold (refer to YES route in step S 31 ), the management node  1  rebalances the selection of the storage nodes  3  (step S 32 ). As a result, it is possible to prevent increase of a load on a specific storage node  3  and deterioration in performance, and resources can be equally allocated to workloads by reducing the difference between the loads. Then, the processing for rebalancing the storage nodes  3  ends. 
     According to the following equation, an average, a difference d, and a variance D of the network slack are obtained, and when the variance D exceeds a threshold t, rebalancing is performed. 
                       d   i     =       s   i     -     s   _         ,     D   =       ∑     i   =   1     n           d   i   2                 [     Expression   ⁢         2     ]               
(NETWORK SLACKS OF STORAGE NODES #1, #2, . . . , #n: s 1 , s 2 , . . . , s n . AVERAGE OF NETWORK SLACK:  s )
 
     Then, rebalancing is performed according to the following procedures (1) to (4). 
     (1) The following sets G and L are defined.
 
 G ={STORAGE NODE i   s   i   ≥ s +t},L ={STORAGE NODE i   |s   i   ≤ s −t}   [Expression 3]
 
     (2) A set V of volumes of which replicas belong to both of the sets G and L is extracted. 
     (3) One volume is select from among the set V, and load allocation is moved from the set G to the set L. 
     (4) Repeat until a difference between the bands of the volumes belonging to the sets G and L becomes equal to or less than a certain value or there is no candidate volume to be moved. 
     [B] Effects 
     According to the management node  1 , the storage system  100 , and the information processing method in the example of the embodiment described above, for example, the following effects can be obtained. 
     When executing the container, the management node  1  acquires the workload load information  131  and system load information (in other words, compute node load information  133 , accelerator load information  134 , and storage node load information  135 ). When the workload  210  is activated, the management node  1  determines the arrangement destination of the workload  210  and the replica position of the volume on the basis of the workload load information  131  and the system load information. 
     As a result, it is possible to distribute the loads in the storage system  100  and improve the throughput. Specifically, for example, it is possible to effectively utilize the resources of the cluster including the communication and the storages. Therefore, more applications can be executed with the same system. 
     The management node  1  selects the first compute node  2  of which the sum of the communication amount between the processor  11  and the network  170 , the communication amount between the processor  11  and the volume, and the communication amount between the accelerator  220  and the volume is equal to or less than the margin in the network  170  from among the plurality of compute nodes  2 . Furthermore, the management node  1  selects the second compute node  2  of which the sum of the communication amount between the processor  11  and the network  170 , the communication amount between the processor  11  and the volume, and the communication amount between the processor  11  and the accelerator  220  is equal to or less than the margin in the network  170  from among the plurality of compute nodes  2 . The management node  1  determines the first compute node  2  or the second compute node  2  as the arrangement destination of the workload  210 . 
     As a result, an appropriate compute node  2  can be selected as the arrangement destination of the workload  210 . 
     The management node  1  selects one or more first storage nodes  3  of which the sum of the communication amount between the processor  11  and the volume and the communication amount between the accelerator  220  and the volume is equal to or less than the margin in the network  170  from among the plurality of storage nodes  3 . The management node  1  determines the one or more first storage nodes  3  as the replica positions. 
     As a result, an appropriate storage node  3  can be selected as the replica position of the volume. 
     When a difference between the loads of the plurality of storage nodes  3  included in the storage system  100  exceeds the threshold, the management node  1  determines the replica position. 
     As a result, it is possible to prevent increase of a load on a specific storage node  3  and deterioration in performance, and resources can be equally allocated to workloads by reducing the difference between the loads. 
     [C] Others 
     The disclosed technique is not limited to the embodiment described above, and various modifications may be made without departing from the spirit of the present embodiment. Each configuration and each processing according to the present embodiment may be selected as needed, or may also be combined as appropriate. 
     All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.