Patent Publication Number: US-10318445-B2

Title: Priority level adaptation in a dispersed storage network

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present U.S. Utility Patent Application claims priority pursuant to 35 U.S.C. § 120 as a continuation-in-part of U.S. Utility application Ser. No. 13/683,951, entitled “PRIORITIZATION OF MESSAGES OF A DISPERSED STORAGE NETWORK”, filed Nov. 21, 2012, which claims priority pursuant to 35 U.S.C. § 119(e) to U.S. Provisional Application No. 61/564,185, entitled “OPTIMIZING PERFORMANCE OF DISPERSED STORAGE NETWORK”, filed Nov. 28, 2011, both of which are hereby incorporated herein by reference in their entirety and made part of the present U.S. Utility Patent Application for all purposes. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     Technical Field of the Invention 
     This invention relates generally to computer networks and more particularly to dispersing error encoded data. 
     Description of Related Art 
     Computing devices are known to communicate data, process data, and/or store data. Such computing devices range from wireless smart phones, laptops, tablets, personal computers (PC), work stations, and video game devices, to data centers that support millions of web searches, stock trades, or on-line purchases every day. In general, a computing device includes a central processing unit (CPU), a memory system, user input/output interfaces, peripheral device interfaces, and an interconnecting bus structure. 
     As is further known, a computer may effectively extend its CPU by using “cloud computing” to perform one or more computing functions (e.g., a service, an application, an algorithm, an arithmetic logic function, etc.) on behalf of the computer. Further, for large services, applications, and/or functions, cloud computing may be performed by multiple cloud computing resources in a distributed manner to improve the response time for completion of the service, application, and/or function. For example, Hadoop is an open source software framework that supports distributed applications enabling application execution by thousands of computers. 
     In addition to cloud computing, a computer may use “cloud storage” as part of its memory system. As is known, cloud storage enables a user, via its computer, to store files, applications, etc. on an Internet storage system. The Internet storage system may include a RAID (redundant array of independent disks) system and/or a dispersed storage system that uses an error correction scheme to encode data for storage. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG. 1  is a schematic block diagram of an embodiment of a dispersed or distributed storage network (DSN) in accordance with the present invention; 
         FIG. 2  is a schematic block diagram of an embodiment of a computing core in accordance with the present invention; 
         FIG. 3  is a schematic block diagram of an example of dispersed storage error encoding of data in accordance with the present invention; 
         FIG. 4  is a schematic block diagram of a generic example of an error encoding function in accordance with the present invention; 
         FIG. 5  is a schematic block diagram of a specific example of an error encoding function in accordance with the present invention; 
         FIG. 6  is a schematic block diagram of an example of a slice name of an encoded data slice (EDS) in accordance with the present invention; 
         FIG. 7  is a schematic block diagram of an example of dispersed storage error decoding of data in accordance with the present invention; 
         FIG. 8  is a schematic block diagram of a generic example of an error decoding function in accordance with the present invention; 
         FIG. 9A  is a schematic block diagram of an embodiment of storage module in accordance with the present invention; 
         FIG. 9B  is a schematic block diagram of an embodiment of computing system in accordance with the present invention; and 
         FIG. 10  is a logic diagram of an example of a method of in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a schematic block diagram of an embodiment of a dispersed, or distributed, storage network (DSN)  10  that includes a plurality of computing devices  12 - 16 , a managing unit  18 , an integrity processing unit  20 , and a DSN memory  22 . The components of the DSN  10  are coupled to a network  24 , which may include one or more wireless and/or wire lined communication systems; one or more non-public intranet systems and/or public internet systems; and/or one or more local area networks (LAN) and/or wide area networks (WAN). 
     The DSN memory  22  includes a plurality of storage units  36  that may be located at geographically different sites (e.g., one in Chicago, one in Milwaukee, etc.), at a common site, or a combination thereof. For example, if the DSN memory  22  includes eight storage units  36 , each storage unit is located at a different site. As another example, if the DSN memory  22  includes eight storage units  36 , all eight storage units are located at the same site. As yet another example, if the DSN memory  22  includes eight storage units  36 , a first pair of storage units are at a first common site, a second pair of storage units are at a second common site, a third pair of storage units are at a third common site, and a fourth pair of storage units are at a fourth common site. Note that a DSN memory  22  may include more or less than eight storage units  36 . Further note that each storage unit  36  includes a computing core (as shown in  FIG. 2 , or components thereof) and a plurality of memory devices for storing dispersed error encoded data. 
     In various embodiments, each of the storage units operates as a distributed storage and task (DST) execution unit, and is operable to store dispersed error encoded data and/or to execute, in a distributed manner, one or more tasks on data. The tasks may be a simple function (e.g., a mathematical function, a logic function, an identify function, a find function, a search engine function, a replace function, etc.), a complex function (e.g., compression, human and/or computer language translation, text-to-voice conversion, voice-to-text conversion, etc.), multiple simple and/or complex functions, one or more algorithms, one or more applications, etc. Hereafter, a storage unit may be interchangeably referred to as a DST execution unit and a set of storage units may be interchangeably referred to as a set of DST execution units. 
     Each of the computing devices  12 - 16 , the managing unit  18 , and the integrity processing unit  20  include a computing core  26 , which includes network interfaces  30 - 33 . Computing devices  12 - 16  may each be a portable computing device and/or a fixed computing device. A portable computing device may be a social networking device, a gaming device, a cell phone, a smart phone, a digital assistant, a digital music player, a digital video player, a laptop computer, a handheld computer, a tablet, a video game controller, and/or any other portable device that includes a computing core. A fixed computing device may be a computer (PC), a computer server, a cable set-top box, a satellite receiver, a television set, a printer, a fax machine, home entertainment equipment, a video game console, and/or any type of home or office computing equipment. Note that each of the managing unit  18  and the integrity processing unit  20  may be separate computing devices, may be a common computing device, and/or may be integrated into one or more of the computing devices  12 - 16  and/or into one or more of the storage units  36 . 
     Each interface  30 ,  32 , and  33  includes software and hardware to support one or more communication links via the network  24  indirectly and/or directly. For example, interface  30  supports a communication link (e.g., wired, wireless, direct, via a LAN, via the network  24 , etc.) between computing devices  14  and  16 . As another example, interface  32  supports communication links (e.g., a wired connection, a wireless connection, a LAN connection, and/or any other type of connection to/from the network  24 ) between computing devices  12  &amp;  16  and the DSN memory  22 . As yet another example, interface  33  supports a communication link for each of the managing unit  18  and the integrity processing unit  20  to the network  24 . 
     Computing devices  12  and  16  include a dispersed storage (DS) client module  34 , which enables the computing device to dispersed storage error encode and decode data as subsequently described with reference to one or more of  FIGS. 3-8 . In this example embodiment, computing device  16  functions as a dispersed storage processing agent for computing device  14 . In this role, computing device  16  dispersed storage error encodes and decodes data on behalf of computing device  14 . With the use of dispersed storage error encoding and decoding, the DSN  10  is tolerant of a significant number of storage unit failures (the number of failures is based on parameters of the dispersed storage error encoding function) without loss of data and without the need for a redundant or backup copies of the data. Further, the DSN  10  stores data for an indefinite period of time without data loss and in a secure manner (e.g., the system is very resistant to unauthorized attempts at accessing the data). 
     In operation, the managing unit  18  performs DS management services. For example, the managing unit  18  establishes distributed data storage parameters (e.g., vault creation, distributed storage parameters, security parameters, billing information, user profile information, etc.) for computing devices  12 - 14  individually or as part of a group of user devices. As a specific example, the managing unit  18  coordinates creation of a vault (e.g., a virtual memory block associated with a portion of an overall namespace of the DSN) within the DSN memory  22  for a user device, a group of devices, or for public access and establishes per vault dispersed storage (DS) error encoding parameters for a vault. The managing unit  18  facilitates storage of DS error encoding parameters for each vault by updating registry information of the DSN  10 , where the registry information may be stored in the DSN memory  22 , a computing device  12 - 16 , the managing unit  18 , and/or the integrity processing unit  20 . 
     The DSN managing unit  18  creates and stores user profile information (e.g., an access control list (ACL)) in local memory and/or within memory of the DSN memory  22 . The user profile information includes authentication information, permissions, and/or the security parameters. The security parameters may include encryption/decryption scheme, one or more encryption keys, key generation scheme, and/or data encoding/decoding scheme. 
     The DSN managing unit  18  creates billing information for a particular user, a user group, a vault access, public vault access, etc. For instance, the DSN managing unit  18  tracks the number of times a user accesses a non-public vault and/or public vaults, which can be used to generate a per-access billing information. In another instance, the DSN managing unit  18  tracks the amount of data stored and/or retrieved by a user device and/or a user group, which can be used to generate a per-data-amount billing information. 
     As another example, the managing unit  18  performs network operations, network administration, and/or network maintenance. Network operations includes authenticating user data allocation requests (e.g., read and/or write requests), managing creation of vaults, establishing authentication credentials for user devices, adding/deleting components (e.g., user devices, storage units, and/or computing devices with a DS client module  34 ) to/from the DSN  10 , and/or establishing authentication credentials for the storage units  36 . Network administration includes monitoring devices and/or units for failures, maintaining vault information, determining device and/or unit activation status, determining device and/or unit loading, and/or determining any other system level operation that affects the performance level of the DSN  10 . Network maintenance includes facilitating replacing, upgrading, repairing, and/or expanding a device and/or unit of the DSN  10 . 
     The integrity processing unit  20  performs rebuilding of ‘bad’ or missing encoded data slices. At a high level, the integrity processing unit  20  performs rebuilding by periodically attempting to retrieve/list encoded data slices, and/or slice names of the encoded data slices, from the DSN memory  22 . For retrieved encoded slices, they are checked for errors due to data corruption, outdated version, etc. If a slice includes an error, it is flagged as a ‘bad’ slice. For encoded data slices that were not received and/or not listed, they are flagged as missing slices. Bad and/or missing slices are subsequently rebuilt using other retrieved encoded data slices that are deemed to be good slices to produce rebuilt slices. The rebuilt slices are stored in the DSN memory  22 . 
       FIG. 2  is a schematic block diagram of an embodiment of a computing core  26  that includes a processing module  50 , a memory controller  52 , main memory  54 , a video graphics processing unit  55 , an input/output (IO) controller  56 , a peripheral component interconnect (PCI) interface  58 , an IO interface module  60 , at least one IO device interface module  62 , a read only memory (ROM) basic input output system (BIOS)  64 , and one or more memory interface modules. The one or more memory interface module(s) includes one or more of a universal serial bus (USB) interface module  66 , a host bus adapter (HBA) interface module  68 , a network interface module  70 , a flash interface module  72 , a hard drive interface module  74 , and a DSN interface module  76 . 
     The DSN interface module  76  functions to mimic a conventional operating system (OS) file system interface (e.g., network file system (NFS), flash file system (FFS), disk file system (DFS), file transfer protocol (FTP), web-based distributed authoring and versioning (WebDAV), etc.) and/or a block memory interface (e.g., small computer system interface (SCSI), internet small computer system interface (iSCSI), etc.). The DSN interface module  76  and/or the network interface module  70  may function as one or more of the interface  30 - 33  of  FIG. 1 . Note that the IO device interface module  62  and/or the memory interface modules  66 - 76  may be collectively or individually referred to as IO ports. 
       FIG. 3  is a schematic block diagram of an example of dispersed storage error encoding of data. When a computing device  12  or  16  has data to store it disperse storage error encodes the data in accordance with a dispersed storage error encoding process based on dispersed storage error encoding parameters. Here, the computing device stores data object  40 , which can include a file (e.g., text, video, audio, etc.), or other data arrangement. The dispersed storage error encoding parameters include an encoding function (e.g., information dispersal algorithm, Reed-Solomon, Cauchy Reed-Solomon, systematic encoding, non-systematic encoding, on-line codes, etc.), a data segmenting protocol (e.g., data segment size, fixed, variable, etc.), and per data segment encoding values. The per data segment encoding values include a total, or pillar width, number (T) of encoded data slices per encoding of a data segment i.e., in a set of encoded data slices); a decode threshold number (D) of encoded data slices of a set of encoded data slices that are needed to recover the data segment; a read threshold number (R) of encoded data slices to indicate a number of encoded data slices per set to be read from storage for decoding of the data segment; and/or a write threshold number (W) to indicate a number of encoded data slices per set that must be accurately stored before the encoded data segment is deemed to have been properly stored. The dispersed storage error encoding parameters may further include slicing information (e.g., the number of encoded data slices that will be created for each data segment) and/or slice security information (e.g., per encoded data slice encryption, compression, integrity checksum, etc.). 
     In the present example, Cauchy Reed-Solomon has been selected as the encoding function (a generic example is shown in  FIG. 4  and a specific example is shown in  FIG. 5 ); the data segmenting protocol is to divide the data object into fixed sized data segments; and the per data segment encoding values include: a pillar width of 5, a decode threshold of 3, a read threshold of 4, and a write threshold of 4. In accordance with the data segmenting protocol, the computing device  12  or  16  divides data object  40  into a plurality of fixed sized data segments (e.g., 1 through Y of a fixed size in range of Kilo-bytes to Tera-bytes or more). The number of data segments created is dependent of the size of the data and the data segmenting protocol. 
     The computing device  12  or  16  then disperse storage error encodes a data segment using the selected encoding function (e.g., Cauchy Reed-Solomon) to produce a set of encoded data slices.  FIG. 4  illustrates a generic Cauchy Reed-Solomon encoding function, which includes an encoding matrix (EM), a data matrix (DM), and a coded matrix (CM). The size of the encoding matrix (EM) is dependent on the pillar width number (T) and the decode threshold number (D) of selected per data segment encoding values. To produce the data matrix (DM), the data segment is divided into a plurality of data blocks and the data blocks are arranged into D number of rows with Z data blocks per row. Note that Z is a function of the number of data blocks created from the data segment and the decode threshold number (D). The coded matrix is produced by matrix multiplying the data matrix by the encoding matrix. 
       FIG. 5  illustrates a specific example of Cauchy Reed-Solomon encoding with a pillar number (T) of five and decode threshold number of three. In this example, a first data segment is divided into twelve data blocks (D 1 -D 12 ). The coded matrix includes five rows of coded data blocks, where the first row of X 11 -X 14  corresponds to a first encoded data slice (EDS  1 _ 1 ), the second row of X 21 -X 24  corresponds to a second encoded data slice (EDS  2 _ 1 ), the third row of X 31 -X 34  corresponds to a third encoded data slice (EDS  3 _ 1 ), the fourth row of X 41 -X 44  corresponds to a fourth encoded data slice (EDS  4 _ 1 ), and the fifth row of X 51 -X 54  corresponds to a fifth encoded data slice (EDS  5 _ 1 ). Note that the second number of the EDS designation corresponds to the data segment number. 
     Returning to the discussion of  FIG. 3 , the computing device also creates a slice name (SN) for each encoded data slice (EDS) in the set of encoded data slices. A typical format for a slice name  80  is shown in  FIG. 6 . As shown, the slice name (SN)  80  includes a pillar number of the encoded data slice (e.g., one of 1-T), a data segment number (e.g., one of 1-Y), a vault identifier (ID), a data object identifier (ID), and may further include revision level information of the encoded data slices. The slice name functions as, at least part of, a DSN address for the encoded data slice for storage and retrieval from the DSN memory  22 . 
     As a result of encoding, the computing device  12  or  16  produces a plurality of sets of encoded data slices, which are provided with their respective slice names to the storage units for storage. As shown, the first set of encoded data slices includes EDS  1 _ 1  through EDS  5 _ 1  and the first set of slice names includes SN  1 _ 1  through SN  5 _ 1  and the last set of encoded data slices includes EDS  1 _Y through EDS  5 _Y and the last set of slice names includes SN  1 _Y through SN  5 _Y. 
       FIG. 7  is a schematic block diagram of an example of dispersed storage error decoding of a data object that was dispersed storage error encoded and stored in the example of  FIG. 4 . In this example, the computing device  12  or  16  retrieves from the storage units at least the decode threshold number of encoded data slices per data segment. As a specific example, the computing device retrieves a read threshold number of encoded data slices. 
     To recover a data segment from a decode threshold number of encoded data slices, the computing device uses a decoding function as shown in  FIG. 8 . As shown, the decoding function is essentially an inverse of the encoding function of  FIG. 4 . The coded matrix includes a decode threshold number of rows (e.g., three in this example) and the decoding matrix in an inversion of the encoding matrix that includes the corresponding rows of the coded matrix. For example, if the coded matrix includes rows 1, 2, and 4, the encoding matrix is reduced to rows 1, 2, and 4, and then inverted to produce the decoding matrix. 
       FIG. 9A  is a schematic block diagram of an embodiment of a storage module  84  that includes a writer  102 , a reader  104 , and queues  1 - 5 . The storage module  84  can be implemented via a computing device  16  of  FIG. 1 , the network  24  of  FIG. 1 . The computing device  16  can function as a dispersed storage processing agent for computing device  14  as described previously, and may hereafter be referred to as a distributed storage and task (DST) processing unit. Each dispersed storage (DS) unit  1 - 5  may be implemented utilizing the storage unit  36  of  FIG. 1 . While the DST processing unit is described below in conjunction with the operation of computing unit  16 , the operates may likewise be performed by other DST processing units, including integrity processing unit  20  and/or managing unit  18  of  FIG. 1 . 
     The writer  102  generates messages for transmission to one or more DS units of DS units  1 - 5 . The reader  104  interprets messages received from the one or more DS units of DS units  1 - 5 . The messages include request messages and response messages. Messages transmitted from the storage module  84  to DS units  1 - 5  include requests  1 - 5 . Messages that the storage module  84  receives from DS units  1 - 5  include responses  1 - 5 . 
     Each queue of queues  1 - 5  may be implemented as one or more of a physical memory device, a plurality of memory devices, and a virtual allocation of storage capacity of one or more memory devices. Each queue may be associated with a fixed storage capacity. Each queue of queues  1 - 5  temporarily stores messages received from a DS unit waiting to be processed by the reader  104  or messages from the writer  102  to be transmitted to a DS unit. For example, the writer  102  stores message  3 - 5  in queue  3  for transmission to DS unit  3 . Message  3 - 5  are sent to DS unit  3  via a network when message  3 - 5  are to be transmitted in accordance with a queue prioritization scheme. 
     The queue prioritization scheme may be based on one or more of a number of messages associated with the queue (e.g., pending messages), a prioritization approach (e.g., first in first out (FIFO), last in last out (LIFO)), a prioritization level associated with each of the messages associated with the queue, a network performance level, a DS unit performance level, and an order of message receipt by the queue. For instance, queue  3  outputs message  3 - 5  to DS unit  3  when messages  3 - 1  through  3 - 4  have been successfully sent in accordance with a FIFO prioritization approach of the queue prioritization scheme. As another instance, queue  3  outputs message  3 - 5  to DS unit  3  when message  3 - 1  has been successfully sent and prior to sending of messages  3 - 2  through  3 - 4  when a prioritization level associated with message  3 - 5  is greater than a privatization level associated with messages  3 - 2  through  3 - 4  and the prioritization level associated with message  3 - 5  is lower than a privatization level associated with message  3 - 1 . As another example, queue  4  receives message  4 - 0  from DS unit  4  to be read by the reader  104 . Queue  4  outputs message  4 - 0  to the reader  104  in accordance with the queue prioritization scheme. 
     The storage module  84  may delete a message stored in a queue when the message is outputted and is no longer required. The storage module  84  may change a message priority level of the message after message has been stored in a queue to affect a modified message transmission order. The storage module  84  may delete the message stored in the queue when the message is no longer required. The method to determine whether the message is no longer required, to delete the message, and to change the message priority is discussed in greater detail with reference to  FIGS. 6B-10 . 
       FIG. 9B  is a schematic block diagram of another embodiment of a computing system that includes a computing device  110  and a dispersed storage network (DSN) memory  22  of a dispersed storage network. The DSN memory  22  includes a plurality of storage nodes  112 - 116 . The computing device  110  includes a dispersed storage (DS) processing  118 . The computing device  110  may be implemented as at least one of a user device, a DS processing unit, and a DS unit. The DS processing  118  includes a generate messages module  120 , a processing information module  122 , a prioritization module  124 , and a messaging module  126 . The system functions to access the DSN memory  22  with regards to a set of encoded data slices. The accessing includes at least one of reading the set of encoded data slices from the DSN memory  22  and writing the set of encoded data slices to the DSN memory  22 . A data segment  128  of data is encoded using a dispersed storage error coding function to produce the set of encoded data slices. The generate messages module  120  receives the data segment  128  when the accessing includes writing the set of encoded data slices to the DSN memory  22 . For example, the generate messages module  120  receives the data segment  128  and encodes the data segment  128  to produce the set of encoded data slices when the accessing includes writing the set of encoded data slices to the DSN memory  22 . As another example, the DS processing  118  generates the data segment  128  and encodes the data segment  128  to produce the set of encoded data slices when the accessing includes writing the set of encoded data slices to the DSN memory  22 . Alternatively, the generate messages module  120  receives the set of encoded data slices. 
     The generate messages module  120  generates a set of messages  130  regarding the set of encoded data slices. The set of messages  130  includes a set of read messages to read the set of encoded data slices from the DSN memory  22  when the accessing includes reading the set of encoded data slices from the DSN memory  22 . A read message of the set of read messages includes a read slice request. For example, the generate messages module  120  generates a set of read slice requests that includes a set of slice names corresponding to the set of encoded data slices. The set of messages  130  includes a set of write messages to write the set of encoded data slices to the DSN memory  22  when the accessing includes writing the set of encoded data slices to the DSN memory  22 . A write message of the set of write messages includes a write slice request. For example, the generate messages module  120  generates a set of write slice requests that includes the set of encoded data slices and the set of slice names corresponding to the set of encoded data slices. 
     The processing information module  122  determines system-level message processing information  132  based on status of processing a plurality of sets of messages regarding a plurality of sets of encoded data slices. The plurality of sets of messages regarding the plurality of sets of encoded data slices may include numerous other write and read accesses of other encoded data slices within at least one storage node of the plurality of storage nodes  112 - 116 . The processing information module  122  determines the system-level message processing information  132  by a series of steps. A first step includes, for a first set of messages of the plurality of sets of messages, determining at least one of: a current status of sending the first set of messages (e.g., the first set of messages have been sent to the DSN memory  22 ), and a current status of successfully processing the first set of messages. The determining includes at least one of initiating a query, performing a lookup, executing a test, accessing historical records, and accessing the messaging module  126 . The processing of the first set of messages includes at least one of retrieving and writing the set of encoded data slices. For example, a current status of sending the first set of messages indicates that 5 messages of a set of 16 messages have been sent. Successfully processing the first set of messages may include at least one of retrieving at least a decode threshold number of encoded data slices of the set of encoded data slices and writing at least a write threshold number of encoded data slices of the set of encoded data slices. For example, a current status of successfully processing the first set of messages indicates successful processing when 11 encoded data slices have been retrieved when a decode threshold number is 10. As another example, a current status of successfully processing the first set of messages indicates unsuccessful processing when 12 encoded data slices have been sent when a write threshold number is 13. 
     A second step of determining the system-level message processing information includes, for a second set of messages of the plurality of sets of messages, determining at least one of: a current status of sending the second set of messages, and a current status of successfully processing the second set of messages. Alternatively, or in addition to, more steps may be included in the series of steps including determining status with regards to further sets of messages of the plurality of sets of messages. A third step includes, determining the status of processing the plurality of sets of messages regarding the plurality of sets of encoded data slices based on the at least one of the current status of sending the first set of messages and the current status of successfully processing of the first set of messages, and the at least one of the current status of sending the second set of messages, and the current status of successfully processing of the second set of messages. The determining includes at least one of aggregating status, selecting status, and confirming status. For example, the processing information module  122  determines the status of processing the plurality sets of messages regarding the plurality of sets of encoded data slices by aggregating current status associated with 10 sets of messages when the plurality of sets of messages includes 10 sets of messages. 
     For a first message  136  of the set of messages  130 , the prioritization module  124  determines a first message priority  134  based on the system-level message processing information  132  and message processing status of a first storage node  112  of the plurality of storage nodes  112 - 116 . The prioritization module  124  determines the message processing status of the first storage node  112  by a series of steps. A first step includes determining a number of sets of the plurality of sets of messages that involves the first storage node (e.g., messages to be sent to the first storage node  112 ). A second step includes determining status of sending messages of the number of sets of the plurality of sets of messages to the first storage node  112 . A third step includes determining status of successfully processed messages of the number of sets of the plurality of sets of messages by the first storage node  112 . A fourth step includes determining the message processing status of the first storage node  112  based on the status of sending messages and the status of successfully processed messages. 
     The prioritization module  124  determines the first message priority  134  by a series of steps. A first step includes determining the number of sets of the plurality of sets of messages that involves the first storage node  112 . A second step includes interpreting the system-level message processing information  132  regarding the number of sets that involve the first storage node  112  to produce interpreted system-level message processing information. A third step includes interpreting the message processing status of the first storage node  112  regarding the number of sets that involve the first storage node  112  to produce interpreted message processing status. A fourth step includes applying a load balancing function in accordance the interpreted system-level message processing information and the interpreted message processing status to produce the first message priority  134 . The load balancing function includes at least one of a first in first out function, a last in first out function, a time-based function, and a threshold-based function. For example, the prioritization module  124  produces the first message priority  134  to include a lower than average priority level when the interpreted system-level message processing information indicates that a plurality of other messages are pending to be sent to the first storage node  112  where the plurality of other messages are associated with sets of encoded data slices that have not achieved processing of a threshold number of each set of the sets of encoded data slices. The messaging module  126  sends the first message  136  of the set of messages  130  to the first storage node  112  in accordance with the first message priority  134 . For example, the messaging module  126  sends the first message  136  to the first storage node  112  subsequent to sending another message to the first storage node  112  when a message priority of the other message has greater priority than priority of the first message priority  134 . 
     For a second message  140  of the set of messages  130 , the prioritization module  124  determines a second message priority  138  based on the system-level message processing information  132  and message processing status of a second storage node  114  of the plurality of storage nodes  112 - 116 . The messaging module  126  sends the second message  140  of the set of messages  130  to the second storage node  114  in accordance with the second message priority  138 . For example, the messaging module  126  sends the second message  140  to the second storage node  114  prior to sending a different message to the second storage node  114  when a message priority of the different message has less priority than priority of the second message priority  138 . 
     The system further functions to update message priorities. The prioritization module  124  updates the first message priority  134  based on status of processing the set of messages  130 . The prioritization module  124  updates the second message priority  138  based on status of processing the set of messages  130 . The updating of message priority includes updating message priority associated with writing the set of encoded data slices to the DSN memory  22  and reading the set of encoded data slices from the DSN memory  22 . The status of processing the sets of messages  130  includes status with regards to at least one of a number of messages of the set of messages that have been sent and/or processed and a number of messages of the set of messages that have been sent and/or processed within a given time period. 
     When the set of messages  130  includes the set of write messages to write the set of encoded data slices to the DSN memory  22 , the messaging module  126  determines when a write threshold number of the set of write messages have been sent to the DSN memory  22 . When the write threshold number of the set of write messages have been sent and the first message  136  has not yet been sent to the first storage node  112 , the prioritization module  124  reduces the first message priority  134 . Alternatively, the messaging module  126  determines when a write threshold number of the set of write messages have been successfully processed by the DSN memory  22 . When the write threshold number of the set of write messages have been successfully processed and the first message  136  has not yet been sent to the first storage node  112 , the prioritization module  124  reduces the first message priority  134 . 
     When the set of messages  130  includes the set of read messages to read the set of encoded data slices from the DSN memory  22 , the messaging module  126  determines when a decode threshold number of the set of read messages have been sent to the DSN memory  22 . When the decode threshold number of the set of read messages have been sent and the first message  136  has not yet been sent to the first storage node  112 , the prioritization module  124  reduces the first message priority  134 . Alternatively, the messaging module  126  determines when a decode threshold number of the set of read messages have been successfully processed by the DSN memory  22 . When the decode threshold number of the set of read messages have been successfully processed and the first message  136  has not yet been sent to the first storage node  112 , the prioritization module  124  reduces the first message priority  134 . 
     When the set of messages  130  includes the set of write messages to write the set of encoded data slices to the DSN memory  22 , the messaging module  126  determines that a write threshold number of the set of write messages have not been sent to DSN memory  22  within a given time frame. When the write threshold number of the set of write messages have not been sent in the given time period and the first message  136  has not yet been sent to the first storage node  112  within the given time period, the prioritization module  124  increases the first message priority  134 . 
     Alternatively, when the set of messages  130  includes the set of write messages to write the set of encoded data slices to the DSN memory  22 , the messaging module  126  determines when a write threshold number of the set of write messages have not been successfully processed by the DSN memory  22  within a given time period. When the write threshold number of the set of write messages have not been successfully processed within the given time period and the first message  136  has not yet been sent to the first storage node  112 , the prioritization module  124  increases the first message priority  134 . 
     When the set of messages includes a set of read messages to read the set of encoded data slices from the DSN memory  22 , the messaging module  126  determines when a decode threshold number of the set of read messages have not been sent to the DSN memory  22  within a given time period. When the decode threshold number of the set of read messages have not been sent within the given time period and the first message  136  has not yet been sent to the first storage node  112  in the given time period, the prioritization module  124  increases the first message priority  134 . 
     Alternatively, when the set of messages  130  includes the set of read messages to read the set of encoded data slices from the DSN memory  22 , the messaging module  126  determines when a decode threshold number of the set of read messages have not been successfully processed by the DSN memory  22  within a given time period. When the decode threshold number of the set of read messages have not been successfully processed within the given time period and the first message  136  has not yet been sent to the first storage node  112 , the prioritization module  124  increases the first message priority  134 . 
       FIG. 10  is a flowchart illustrating another example of modifying a write sequence. In particular, a method is presented for use with one or more functions and features described in conjunction with  FIGS. 1-8 and 9A and 9B . In step  180 , a processing module (e.g., of a dispersed storage (DS) processing module) accesses write sequence information. The write sequence information includes one or more of a queue depth, a priority level of a pending request, age of a pending request, number of favorable write responses received so far, and a write threshold number. The accessing may be based on one or more of retrieving a message queue, lookup, receiving a request, a query, and an error message. 
     The method continues at step  182  where the processing module determines whether to elevate a priority level of a write sequence. The priority level of the write sequence may be utilized in determining a transmission order of two or more pending write request messages of a common queue such that a write request associated with a higher priority level is transmitted prior to a write request associated with a lower priority level. The determining may be based on of the access write sequence information. For example, the processing module determines to elevate the priority level of the write sequence when the write sequence is associated with an oldest write sequence of a plurality of write sequences that has not received a write threshold number of favorable write responses. Each write sequence of the plurality of write sequences may be associated with a different write threshold number. As another example, the processing module determines to elevate the priority level of the write sequence when the write sequence is associated with a highest priority write sequence of the plurality of write sequences that has not received the write threshold number of favorable write responses. 
     The method branches to step  186  when the processing module determines not to elevate the priority level of the write sequence. The method continues to step  184  when the processing module determines to elevate the priority level of the write sequence. The method continues at step  184  where the processing module elevates the priority level of the write sequence. The elevating of the priority level includes at least one of modifying a priority level indicator of an associated write request in a message queue to include a higher priority level number and reordering pending write requests in the queue such that highest priority requests will be transmitted next. The method continues to step  186 . 
     The method continues at step  186  where the processing module determines whether to lower the priority level of the write sequence. The determining may be based on write sequence information. For example, the processing module determines to lower the priority level of the write sequence when the write sequence is associated with a write sequence of a plurality of write sequences that has received a write threshold number of favorable write responses. As another example, the processing module determines to lower the priority level of the write sequence when the write sequence is associated with a highest priority write sequence of the plurality of write sequences that has received the write threshold number of favorable write responses. 
     The method branches to step  190  when the processing module determines not to lower the priority level of the write sequence. The method continues to step  188  when the processing module determines to lower the priority level of the write sequence. The method continues at step  188  where the processing module lowers the priority level of the write sequence. The lowering of the priority level includes at least one of modifying a priority level indicator of an associated write request in a message queue to include a lower priority level number and reordering pending write requests in the queue such that highest priority requests will be transmitted next. The method continues to step  190 . The method continues at step  190  where the method can be repeated as required. 
     In various embodiments, a non-transitory computer readable storage medium includes at least one memory section that stores operational instructions that, when executed by a processing system of a dispersed storage network (DSN) that includes a processor and a memory, causes the processing system to access write sequence information corresponding to a write sequence; determine whether to elevate a priority level of the write sequence; when the processing system determines to elevate the priority level of the write sequence, elevate the priority level of the write sequence; determine whether to lower the priority level of the write sequence; and when the processing system determines to lower the priority level of the write sequence, lower the priority level of the write sequence. 
     It is noted that terminologies as may be used herein such as bit stream, stream, signal sequence, etc. (or their equivalents) have been used interchangeably to describe digital information whose content corresponds to any of a number of desired types (e.g., data, video, speech, audio, etc. any of which may generally be referred to as ‘data’). 
     As may be used herein, the terms “substantially” and “approximately” provides an industry-accepted tolerance for its corresponding term and/or relativity between items. Such an industry-accepted tolerance ranges from less than one percent to fifty percent and corresponds to, but is not limited to, component values, integrated circuit process variations, temperature variations, rise and fall times, and/or thermal noise. Such relativity between items ranges from a difference of a few percent to magnitude differences. As may also be used herein, the term(s) “configured to”, “operably coupled to”, “coupled to”, and/or “coupling” includes direct coupling between items and/or indirect coupling between items via an intervening item (e.g., an item includes, but is not limited to, a component, an element, a circuit, and/or a module) where, for an example of indirect coupling, the intervening item does not modify the information of a signal but may adjust its current level, voltage level, and/or power level. As may further be used herein, inferred coupling (i.e., where one element is coupled to another element by inference) includes direct and indirect coupling between two items in the same manner as “coupled to”. As may even further be used herein, the term “configured to”, “operable to”, “coupled to”, or “operably coupled to” indicates that an item includes one or more of power connections, input(s), output(s), etc., to perform, when activated, one or more its corresponding functions and may further include inferred coupling to one or more other items. As may still further be used herein, the term “associated with”, includes direct and/or indirect coupling of separate items and/or one item being embedded within another item. 
     As may be used herein, the term “compares favorably”, indicates that a comparison between two or more items, signals, etc., provides a desired relationship. For example, when the desired relationship is that signal 1 has a greater magnitude than signal 2, a favorable comparison may be achieved when the magnitude of signal 1 is greater than that of signal 2 or when the magnitude of signal 2 is less than that of signal 1. As may be used herein, the term “compares unfavorably”, indicates that a comparison between two or more items, signals, etc., fails to provide the desired relationship. 
     As may also be used herein, the terms “processing module”, “processing circuit”, “processor”, and/or “processing unit” may be a single processing device or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on hard coding of the circuitry and/or operational instructions. The processing module, module, processing circuit, and/or processing unit may be, or further include, memory and/or an integrated memory element, which may be a single memory device, a plurality of memory devices, and/or embedded circuitry of another processing module, module, processing circuit, and/or processing unit. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. Note that if the processing module, module, processing circuit, and/or processing unit includes more than one processing device, the processing devices may be centrally located (e.g., directly coupled together via a wired and/or wireless bus structure) or may be distributedly located (e.g., cloud computing via indirect coupling via a local area network and/or a wide area network). Further note that if the processing module, module, processing circuit, and/or processing unit implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory and/or memory element storing the corresponding operational instructions may be embedded within, or external to, the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. Still further note that, the memory element may store, and the processing module, module, processing circuit, and/or processing unit executes, hard coded and/or operational instructions corresponding to at least some of the steps and/or functions illustrated in one or more of the Figures. Such a memory device or memory element can be included in an article of manufacture. 
     One or more embodiments have been described above with the aid of method steps illustrating the performance of specified functions and relationships thereof. The boundaries and sequence of these functional building blocks and method steps have been arbitrarily defined herein for convenience of description. Alternate boundaries and sequences can be defined so long as the specified functions and relationships are appropriately performed. Any such alternate boundaries or sequences are thus within the scope and spirit of the claims. Further, the boundaries of these functional building blocks have been arbitrarily defined for convenience of description. Alternate boundaries could be defined as long as the certain significant functions are appropriately performed. Similarly, flow diagram blocks may also have been arbitrarily defined herein to illustrate certain significant functionality. 
     To the extent used, the flow diagram block boundaries and sequence could have been defined otherwise and still perform the certain significant functionality. Such alternate definitions of both functional building blocks and flow diagram blocks and sequences are thus within the scope and spirit of the claims. One of average skill in the art will also recognize that the functional building blocks, and other illustrative blocks, modules and components herein, can be implemented as illustrated or by discrete components, application specific integrated circuits, processors executing appropriate software and the like or any combination thereof. 
     In addition, a flow diagram may include a “start” and/or “continue” indication. The “start” and “continue” indications reflect that the steps presented can optionally be incorporated in or otherwise used in conjunction with other routines. In this context, “start” indicates the beginning of the first step presented and may be preceded by other activities not specifically shown. Further, the “continue” indication reflects that the steps presented may be performed multiple times and/or may be succeeded by other activities not specifically shown. Further, while a flow diagram indicates a particular ordering of steps, other orderings are likewise possible provided that the principles of causality are maintained. 
     The one or more embodiments are used herein to illustrate one or more aspects, one or more features, one or more concepts, and/or one or more examples. A physical embodiment of an apparatus, an article of manufacture, a machine, and/or of a process may include one or more of the aspects, features, concepts, examples, etc. described with reference to one or more of the embodiments discussed herein. Further, from figure to figure, the embodiments may incorporate the same or similarly named functions, steps, modules, etc. that may use the same or different reference numbers and, as such, the functions, steps, modules, etc. may be the same or similar functions, steps, modules, etc. or different ones. 
     Unless specifically stated to the contra, signals to, from, and/or between elements in a figure of any of the figures presented herein may be analog or digital, continuous time or discrete time, and single-ended or differential. For instance, if a signal path is shown as a single-ended path, it also represents a differential signal path. Similarly, if a signal path is shown as a differential path, it also represents a single-ended signal path. While one or more particular architectures are described herein, other architectures can likewise be implemented that use one or more data buses not expressly shown, direct connectivity between elements, and/or indirect coupling between other elements as recognized by one of average skill in the art. 
     The term “module” is used in the description of one or more of the embodiments. A module implements one or more functions via a device such as a processor or other processing device or other hardware that may include or operate in association with a memory that stores operational instructions. A module may operate independently and/or in conjunction with software and/or firmware. As also used herein, a module may contain one or more sub-modules, each of which may be one or more modules. 
     As may further be used herein, a computer readable memory includes one or more memory elements. A memory element may be a separate memory device, multiple memory devices, or a set of memory locations within a memory device. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. The memory device may be in a form a solid state memory, a hard drive memory, cloud memory, thumb drive, server memory, computing device memory, and/or other physical medium for storing digital information. 
     While particular combinations of various functions and features of the one or more embodiments have been expressly described herein, other combinations of these features and functions are likewise possible. The present disclosure is not limited by the particular examples disclosed herein and expressly incorporates these other combinations.