Online Data Volume Deletion via Shadow Memory and Restart Page Relocation
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Solution Overview
Problem
Conventional techniques require a database system to be offline to delete a data volume, which is unsuitable for online operations and can lead to system failures if the data volume containing the restart page is deleted, as it disrupts the system's ability to start properly.
Innovation Solution
A method to delete a data volume while the database system remains online by using a 'shadow memory' feature to write modified pages to other data volumes, updating converter pages to reflect new locations, and relocating the restart page, allowing for efficient data volume deletion and restart page management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the database system enters offline mode to delete a data volume, then the data volume can be deleted safely, but the database system cannot be read or written during this process
Solution Approach 1:
The patent applies preliminary action by copying data from the data volume to be deleted to other data volumes before the deletion operation. This preparatory step ensures that data is safely preserved in alternative locations, allowing the system to proceed with deletion while maintaining operational continuity and avoiding the need for offline mode.
2Quantity of substance
If the data volume containing the restart page is deleted, then storage space is freed, but the database system fails to start properly because it cannot locate the restart page
Solution Approach 1:
The patent extracts the restart page from the data volume to be deleted and relocates it to a separate, preserved data volume. This extraction ensures that the restart page is removed from the deletion target while being safely stored elsewhere, allowing the system to free storage space without compromising startup capability.
Solution Approach 2:
The patent introduces a mediator mechanism in the form of a relocation map that tracks the new location of the restart page. This intermediary structure enables the database system to locate and access the restart page even though it resides in a different data volume than originally configured, thus maintaining startup reliability while enabling deletion of the original volume.
3Ease of manufacture
If conventional deletion techniques are used, then data volume deletion can be performed, but the system must remain offline during the process
Solution Approach 1:
The patent performs preliminary data copying and restart page relocation operations before the deletion process begins. By completing these preparatory actions while the system is online, the actual deletion can proceed without requiring offline mode, thus maintaining ease of operation and system availability.
Solution Approach 2:
The patent enables continuous useful action by allowing the database system to remain operational during the deletion process. Data copying, restart page relocation, and deletion operations are performed in a sequence that maintains system availability, ensuring that read/write operations can continue uninterrupted throughout the deletion process.
Data Source
AI summary
A system to delete a data volume may include storage of a plurality of data pages of the data volume of a data area into a cache, prevention of writing of data pages to the data volume, and designation of each of the plurality of data pages in the cache as modified. The system may also include writing of all data pages in the cache that are designated as modified to a respective location in one or more other data volumes of the data area, and updating, for each of the written data pages, a converter page of the cache to associate the written data page with its respective location in the one or more other data volumes.