Data redundancy in a multiple node system

Abstract

In some examples, a system includes a plurality of nodes connected to one or more networks, and each of the nodes may include at least one processor and one or more storage devices. The system may be configured to store data, and redundancy data for the data, across the plurality of nodes in the system based at least in part on a redundancy policy. Further, each of the nodes may maintain configuration information that indicates a data placement of the data and the redundancy data on the plurality of nodes. In addition, each of the nodes may be configured to have a function to act as a first node which is configured to determine, upon a change of the redundancy policy, updated configuration information for the system based on the change of the redundancy policy.

What is claimed is: 
     
         1 . A system comprising:
 a plurality of nodes connected to one or more networks, each of the nodes comprising at least one processor and one or more storage devices, wherein:
 the system is configured to store data, and redundancy data for the data, across the plurality of nodes in the system based at least in part on a redundancy policy; 
 each of the nodes maintains configuration information that indicates a data placement of the data and the redundancy data on the plurality of nodes; and 
 each of the nodes is configured to have a function to act as a first node which is configured to determine, upon a change of the redundancy policy, updated configuration information for the system based on the change of the redundancy policy. 
   
     
     
         2 . The system as recited in  claim 1 , wherein the redundancy data includes at least one of:
 one or more data replicas of the data; or   one or more erasure-coded segments generated from the data.   
     
     
         3 . The system as recited in  claim 1 , wherein:
 the redundancy policy sets a redundancy level indicating an amount of the redundancy data stored in the system; and   the change in the redundancy policy includes either an increase in the redundancy level or a decrease in the redundancy level, corresponding to either an increase or a decrease, respectively, in the amount of the redundancy data stored in the system.   
     
     
         4 . The system as recited in  claim 1 , wherein a node acting as the first node is further configured to send a first message indicating the change of the redundancy policy to other nodes of the plurality of nodes for either increasing or decreasing an amount of the redundancy data stored in the system. 
     
     
         5 . The system as recited in  claim 4 , wherein, based on the change of the redundancy policy and based on receiving the first message from the first node, the other nodes are configured to at least one of:
 migrate the redundancy data from one or more first locations to one or more second locations on the storage devices of the nodes; or   remove at least one of the data or the redundancy data from one or more of the storage devices of the nodes.   
     
     
         6 . The system as recited in  claim 4 , wherein:
 the configuration information includes first map layout information which is indicative of the data placement of the data and the redundancy data on respective storage devices of the plurality of nodes prior to the change of the redundancy policy, the first map layout information used by individual ones of the nodes to determine a data location of the data and/or redundancy data;   upon receiving the first message from the first node each of the other nodes is configured to create a second map layout information; and   the second map layout information includes a change to a data location of at least one data portion or redundancy data portion based on the change of the redundancy policy included in the first message.   
     
     
         7 . The system as recited in  claim 6 , wherein, based on receiving the first message from the node acting as the first node, and based on determining that the data or the redundancy data stored on a respective node's own one or more storage devices is affected by the change of the redundancy policy, each of the other nodes is configured to calculate a new data location of the data or the redundancy data, respectively, based at least partially on a comparison of the first map layout information and the second map layout information. 
     
     
         8 . A node apparatus for use in a system configured to store, based at least in part on a redundancy policy, data and redundancy data for the data across a plurality of nodes in the system, wherein the plurality of nodes are connected to one or more networks and each of the nodes maintains configuration information that indicates a data placement of the data and the redundancy data on respective storage devices of the nodes in the system, the node apparatus comprising:
 one or more processors; and   one or more of the storage devices coupled to the one or more processors, wherein:
 the node apparatus is configured to act as a first node of the system that determines, upon a change of the redundancy policy, updated configuration information for the system based on the change of the redundancy policy; and/or 
 the node apparatus is configured to act as a second node of the system that is configured to determine whether data stored on its own one or more storage devices is affected by the change of the redundancy policy, based at least in part on updated configuration information received from a node acting as the first node. 
   
     
     
         9 . The node apparatus as recited in  claim 8 , wherein the redundancy data includes at least one of:
 one or more data replicas of the data; or   one or more erasure-coded segments generated from the data.   
     
     
         10 . The node apparatus as recited in  claim 8 , wherein:
 the redundancy policy sets a redundancy level indicating an amount of the redundancy data stored in the system; and   the change in the redundancy policy includes either an increase in the redundancy level or a decrease in the redundancy level, corresponding to either an increase or a decrease, respectively, in the amount of the redundancy data stored in the system.   
     
     
         11 . The node apparatus as recited in  claim 8 , wherein the node apparatus acting as the first node is further configured to send a first message indicating the change of the redundancy policy to other nodes of the plurality of nodes for either increasing or decreasing an amount of the redundancy data stored in the system. 
     
     
         12 . The node apparatus as recited in  claim 11 , wherein when the node apparatus is acting as the second node of the system, upon receiving the first message from a node acting as the first node, the node apparatus is configured to determine whether its own one or more storage devices are affected by the change of the redundancy policy, and based on determining that its own one or more storage devices are affected, at least one of at least one of:
 migrate the redundancy data from one or more first locations to one or more second locations on the storage devices of the nodes; or   remove at least one of the data or the redundancy data from one or more of the storage devices of the nodes.   
     
     
         13 . The node apparatus as recited in  claim 11 , wherein:
 the configuration information includes first map layout information which is indicative of the data placement of the data and the redundancy data on respective storage devices of the plurality of nodes prior to the change of the redundancy policy, the first map layout information used by individual ones of the nodes to determine a data location of the data and/or redundancy data; and   when the node apparatus is acting as the second node, upon receiving the first message from the node acting as the first node, the node apparatus is configured to create second map layout information that includes a change to a data location of at least one data portion or redundancy data portion based on the change of the redundancy policy included in the first message.   
     
     
         14 . One or more non-transitory computer-readable media having executable instructions stored thereon for execution in a system that includes a plurality of nodes connected to one or more networks, each of the nodes comprising at least one processor and one or more storage devices, wherein the system is configured to store data, and redundancy data for the data, across the plurality of nodes in the system based at least in part on a redundancy policy, the executable instructions, when executed, causing one or more of the nodes to perform operations comprising:
 storing, by each of the nodes, configuration information that indicates a data placement of the data and the redundancy data on the plurality of nodes; and   determining, by one of the nodes acting as a first node, based on a change of the redundancy policy, updated configuration information for the system.   
     
     
         15 . The one or more non-transitory computer-readable media as recited in  claim 14 , wherein the redundancy data includes at least one of:
 one or more data replicas of the data; or   one or more erasure-coded segments generated from the data.   
     
     
         16 . The one or more non-transitory computer-readable media as recited in  claim 14 , wherein:
 the redundancy policy sets a redundancy level indicating an amount of the redundancy data stored in the system; and   the change in the redundancy policy includes either an increase in the redundancy level or a decrease in the redundancy level, corresponding to either an increase or a decrease, respectively, in the amount of the redundancy data stored in the system.   
     
     
         17 . The one or more non-transitory computer-readable media as recited in  claim 14 , wherein the node acting as the first node is further configured to send a first message indicating the change of the redundancy policy to other nodes of the plurality of nodes for either increasing or decreasing an amount of the redundancy data stored in the system. 
     
     
         18 . The one or more non-transitory computer-readable media as recited in  claim 17 , wherein, based on the change of the redundancy policy and based on receiving the first message from the first node, the executable instructions, when executed, cause the other nodes to perform operations comprising at least one of:
 migrating the redundancy data from one or more first locations to one or more second locations on the storage devices of the nodes; or   removing at least one of the data or the redundancy data from one or more of the storage devices of the nodes.   
     
     
         19 . The one or more non-transitory computer-readable media as recited in  claim 17 , wherein:
 the configuration information includes first map layout information which is indicative of the data placement of the data and the redundancy data on respective storage devices of the plurality of nodes prior to the change of the redundancy policy, the first map layout information used by individual ones of the nodes to determine a data location of the data and/or redundancy data;   upon receiving the first message from the first node each of the other nodes is configured by the executable instructions to create a second map layout information; and   the second map layout information includes a change to a data location of at least one data portion or redundancy data portion based on the change of the redundancy policy included in the first message.   
     
     
         20 . The one or more non-transitory computer-readable media as recited in  claim 19 , wherein, based on receiving the first message from the node acting as the first node, and based on determining that the data or the redundancy data stored on a respective node's own one or more storage devices is affected by the change of the redundancy policy, the executable instructions configure the other nodes to calculate a new data location of the data or the redundancy data, respectively, based at least partially on a comparison of the first map layout information and the second map layout information.