Clone Volume Split Read Access via Transfer Map
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Solution Overview
Problem
Clone volume split operations in storage systems that tier data to object stores are inefficient due to high network usage, time, and cost, as they require substantial data retrieval and copying, leading to client downtime during the process.
Innovation Solution
The implementation of a transfer map and a reverse map allows for the quick determination of child objects to be created in the object store, enabling read operations during the clone volume split, and issuing copy instructions to copy parent objects as child objects without retrieving them from the object store, thereby reducing network usage and eliminating client downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is retrieved and copied during clone volume split operation, then clone volume becomes independent, but network bandwidth consumption increases
Solution Approach 1:
The patent segments the clone volume split operation into multiple phases: metadata update phase (immediate) and data copy phase (asynchronous). This allows the critical path to be separated from the resource-intensive data copying, enabling independence to be established without immediate full data retrieval.
Solution Approach 2:
The patent performs preliminary actions by updating metadata and creating pointers to data before actual data copying occurs. The transfer map and reverse map are populated in advance, and read access is enabled through these pointers before the data copy completes, avoiding the need to wait for full data retrieval.
2Reliability
If data is retrieved and copied during clone volume split operation, then clone volume becomes independent, but processing time increases
Solution Approach 1:
The patent performs preliminary metadata updates and pointer creations before data copying, enabling the clone volume to be marked as independent immediately. The actual data copying occurs asynchronously in the background, so the processing time for establishing independence is dramatically reduced.
Solution Approach 2:
The patent maintains continuity of useful action by enabling read access during the split operation through the transfer map mechanism. Clients can continue to access data while the copy operation proceeds in the background, eliminating idle time and maintaining productive work flow.
3Reliability
If data is retrieved and copied during clone volume split operation, then clone volume becomes independent, but client downtime increases
Solution Approach 1:
The patent introduces transfer maps and reverse maps as intermediary structures that enable read access during the split operation. These maps act as mediators between clients and the actual data, allowing clients to access data through pointers without waiting for the copy operation to complete.
Solution Approach 2:
The patent performs preliminary metadata updates that enable read access before data copying completes. Clients can begin accessing the clone volume immediately through the transfer map pointers, eliminating downtime while the data copy proceeds asynchronously in the background.
4Reliability
If data is retrieved and copied during clone volume split operation, then clone volume becomes independent, but processing resources increase
Solution Approach 1:
The patent segments the resource-intensive data copying from the critical metadata update operations. By separating these phases, the system can allocate processing resources more efficiently, performing lightweight metadata operations immediately and distributing the heavy data copying workload asynchronously over time.
Data Source
AI summary
Techniques are provided for processing read operations while splitting a clone volume from a parent volume whose data is stored within objects of an object store. A transfer map is created to track mappings of child object identifiers to parent object identifiers of the parent objects to copy as child objects having the child object identifiers. The transfer map for the object store is traversed to copy the parent objects as the child objects for the split clone operation. The child objects are verified as being successfully created with valid data. In response to determining that the parent object has been copied as the child object, a context check is performed using the reverse map to verify a block within the child object. In response a successful context check, the read operation is processed using the block of the child object.