Fault tolerant multi-stage data replication with relaxed coherency guarantees
First Claim
1. A system, comprising:
- one or more processors; and
memory storing program instructions executable by the one or more processors to implement a data replication service configured to;
in response to an update request directed at a data object that includes a plurality of data blocks,update a respective replica of the data object at each primary replica site of a plurality of primary replica sites of the data object, wherein the respective replica includes a respective copy of the data blocks of the data object, wherein updating the respective replica comprises changing data of two or more of the data blocks in the respective copy of the data blocks, wherein the data replication service is configured to update the replicas at the plurality of primary replica sites synchronously with respect to the update request;
store metadata specifying which data blocks were changed by the update at each primary replica site of the plurality of primary replica sites;
in response to determining that a notification of the update is to be sent to a particular additional replica site, send the metadata specifying which data blocks were changed by the update in a notification to the particular additional replica site, wherein the notification does not include the data of the data blocks changed by the update; and
in response to receiving the notification at the particular additional replica site, use the metadata to determine which data blocks were changed by the update, and mark each of the data blocks changed by the update as invalid in an additional replica of the data object at the particular additional replica site, wherein the data replication service is configured to mark the data blocks changed by the update as invalid in the additional replica asynchronously with respect to the update request.
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Abstract
A system for fault tolerant multi-stage data replication with relaxed coherency comprises one or more processors and memory coupled to the processors, where the memory stores program instructions executable by the processors to implement a data replication service. In response to an update request directed at a data object, in a first stage of replication, the data replication service is configured to update respective primary replicas at a plurality of primary replica sites for the data object, and to store metadata descriptors at each of the plurality of primary replica sites. The data replication service is configured to determine whether a notification of the update is to be sent to any other replica sites. In response to identifying such other replica sites, an update notification including contents of a metadata descriptor may be sent to the other replica sites in one or more additional replication stages.
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Citations
26 Claims
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1. A system, comprising:
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one or more processors; and memory storing program instructions executable by the one or more processors to implement a data replication service configured to; in response to an update request directed at a data object that includes a plurality of data blocks, update a respective replica of the data object at each primary replica site of a plurality of primary replica sites of the data object, wherein the respective replica includes a respective copy of the data blocks of the data object, wherein updating the respective replica comprises changing data of two or more of the data blocks in the respective copy of the data blocks, wherein the data replication service is configured to update the replicas at the plurality of primary replica sites synchronously with respect to the update request; store metadata specifying which data blocks were changed by the update at each primary replica site of the plurality of primary replica sites; in response to determining that a notification of the update is to be sent to a particular additional replica site, send the metadata specifying which data blocks were changed by the update in a notification to the particular additional replica site, wherein the notification does not include the data of the data blocks changed by the update; and in response to receiving the notification at the particular additional replica site, use the metadata to determine which data blocks were changed by the update, and mark each of the data blocks changed by the update as invalid in an additional replica of the data object at the particular additional replica site, wherein the data replication service is configured to mark the data blocks changed by the update as invalid in the additional replica asynchronously with respect to the update request. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 25)
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13. A tangible, computer readable medium comprising program instructions, wherein the instructions are computer-executable to implement a data replication service configured to:
in response to an update request directed at a data object that includes a plurality of data blocks, update a respective replica of the data object at each primary replica site of a plurality of primary replica sites of the data object, wherein the respective replica includes a respective copy of the data blocks of the data object, wherein updating the respective replica comprises changing data of two or more of the data blocks in the respective copy of the data blocks wherein the data replication service is configured to update the replicas at the plurality of primary replica sites synchronously with respect to the update request; store metadata specifying which data blocks were changed by the update at each primary replica site of the plurality of primary replica sites; in response to determining that a notification of the update is to be sent to a particular additional replica site, send the metadata specifying which data blocks were changed by the update in a notification to the particular additional replica site, wherein the notification does not include the data of the data blocks changed by the update; and in response to receiving the notification at the particular additional replica site, use the metadata to determine which data blocks were changed by the update, and mark each of the data blocks changed by the update as invalid in an additional replica of the data object at the particular additional replica site, wherein the data replication service is configured to mark the data blocks changed by the update as invalid in the additional replica asynchronously with respect to the update request. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A method comprising:
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updating a respective replica of a data object at each primary replica site of a plurality of primary replica sites of the data object in response to receiving an update request directed at the data object, wherein the respective replica includes a respective copy of a plurality of data blocks of the data object, wherein updating the respective replica comprises changing data of two or more of the data blocks in the respective copy of the data blocks, wherein the replicas at the plurality of primary replica sites are updated synchronously with respect to the update request; storing metadata specifying which data blocks were changed by the update at each primary replica site of the plurality of primary replica sites; in response to determining that a notification of the update is to be sent to a particular additional replica site, sending the metadata specifying which data blocks were changed by the update in a notification to the particular additional replica site, wherein the notification does not include the data of the data blocks changed by the update; and in response to receiving the notification at the particular additional replica site, using the metadata to determine which data blocks were changed by the update, and marking each of the data blocks changed by the update as invalid in an additional replica of the data object at the particular additional replica site, wherein the data blocks changed by the update are marked as invalid in the additional replica asynchronously with respect to the update request. - View Dependent Claims (20, 21, 22, 23, 24)
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26. A system, comprising:
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a plurality of primary replica nodes; and an additional replica node; wherein, in response to a request to update two or more data blocks of a plurality of data blocks of a data object, each respective primary replica node of the plurality of primary replica nodes is configured to update a respective replica of the data object stored at the respective primary replica node by changing data of the two or more data blocks in the respective replica of the data object synchronously with respect to the request; wherein one or more primary replica nodes of the plurality of primary replica nodes are configured to store metadata specifying which data blocks were changed in response to the request; wherein the plurality of primary replica nodes includes a particular primary replica node configured to send the metadata specifying which data blocks were changed in a notification to the additional replica node, wherein the notification does not include the data of the data blocks that were changed; and wherein, in response to receiving the notification, the additional replica node is configured to use the metadata to determine which data blocks were changed, and mark each of the changed data blocks as invalid in an additional replica of the data object stored at the additional replica node, wherein the additional replica node is configured to mark the changed data blocks as invalid in the additional replica asynchronously with respect to the request.
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Specification