Data Migration Using Unused Portion Map to Reduce Bandwidth
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Solution Overview
Problem
Existing data migration methods inefficiently handle unused data portions by transmitting zero data payloads, leading to increased bandwidth consumption and reduced performance during data migration between source and target systems.
Innovation Solution
A method that involves obtaining a map of unused data portions from the source system, using this map to selectively read and write data only from used portions, and marking unused portions on the target system without issuing read requests for zero data payloads, thereby avoiding unnecessary data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional data migration methods are used to read and write all data portions including unused portions, then complete data migration is achieved, but bandwidth consumption increases and performance decreases
Solution Approach 1:
The patent extracts and identifies unused data portions from the logical device using a bitmap structure, then excludes these portions from the data migration process. The bitmap marks each logical address as used or unused, allowing the migration system to selectively read only the necessary data portions, thereby reducing bandwidth consumption while maintaining migration completeness.
Solution Approach 2:
The patent performs preliminary analysis before data migration by creating a bitmap that identifies all unused data portions in advance. This preliminary action allows the migration process to skip unnecessary reads and writes, optimizing bandwidth usage and performance before the actual data transfer begins.
2Reliability
If read commands are issued for all logical addresses during data migration, then all data is transferred, but migration performance decreases due to unnecessary data transmission
Solution Approach 1:
The patent extracts the bitmap information identifying unused logical addresses and uses it to filter out unnecessary read commands. By comparing the bitmap marks against the logical address range, the system generates read commands only for used portions, eliminating wasteful data transmission while ensuring complete migration of necessary data.
Solution Approach 2:
Instead of performing excessive reads for all logical addresses, the patent applies partial action by reading only the necessary used portions identified by the bitmap. This selective reading approach maintains data transfer completeness while significantly improving migration performance by avoiding unnecessary I/O operations.
3Reliability
If zero data payloads are transmitted for unused portions, then data migration protocol is followed, but bandwidth is wasted and efficiency is reduced
Solution Approach 1:
The patent extracts and identifies contiguous unused data portions using the bitmap, then applies special handling to these portions by marking them in the target system without transmitting zero data payloads. This approach maintains protocol compliance for used data while eliminating wasteful bandwidth consumption on unused portions, thereby improving overall migration efficiency.
Data Source
AI summary
Techniques for migrating data of a logical device from a source to a target system may include: obtaining a map indicating unused data portions of a logical device; issuing read commands from the target system to the source system to only read data from the source copy of the logical device for logical addresses that are not marked in the map as unused data portions; receiving the read data at the target system; writing the read data to second logical addresses of the target copy of the logical device on the target system; and marking logical addresses indicated by the map as corresponding to the unused data portions. The source system may also determine whether all data of a received read request that reads data from the logical device is included in an unused data portion and if so, return no read data and a specialized error condition.