Virtual Disk Format Conversion via Granular Block Locking
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Solution Overview
Problem
Conventional storage systems fail to dynamically switch between different virtual disk provisioning types without disrupting running applications, as existing methods either unnecessarily write zeroes or require resource-intensive copying.
Innovation Solution
A file conversion module within the hypervisor uses granular locking and a block-by-block conversion process, leveraging a to-be-zeroed bit field to determine if blocks contain data, thus avoiding unnecessary writes and data loss, and converting disk formats without copying the virtual disk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional storage systems switch between thin and thick provisioning types, then storage space efficiency or performance benefits are achieved, but running applications are disrupted and workloads are interrupted
Solution Approach 1:
The virtual disk is divided into multiple data blocks that can be independently converted between thin and thick provisioning types. The conversion process operates on individual blocks rather than the entire disk, allowing selective transformation without requiring complete disk migration or VM shutdown.
Solution Approach 2:
The storage provisioning type is made dynamically changeable during VM operation. The system allows switching between thin and thick provisioning types on-the-fly without requiring static pre-allocation or complete disk recreation, enabling adaptive storage management while maintaining application continuity.
2Adaptability or versatility
If conventional methods convert virtual disk formats, then format conversion is achieved, but resource-intensive copying processes are required
Solution Approach 1:
The patent extracts and processes only the specific data blocks that require conversion rather than copying the entire virtual disk. By identifying and converting only the necessary blocks (e.g., blocks marked for thick provisioning), the system eliminates redundant data copying operations and reduces overall resource consumption.
Solution Approach 2:
Instead of creating full disk copies for conversion, the system uses block-level operations that copy only specific data blocks when necessary. The to-be-zeroed bit field tracks which blocks need conversion, enabling selective copying rather than blanket disk duplication.
3Ease of manufacture
If conventional conversion processes write zeroes to all blocks, then format conversion is simplified, but unnecessary resource allocation occurs and data may be lost
Solution Approach 1:
The system applies the conversion operation (writing zeroes or allocating blocks) only partially - specifically to data blocks that meet certain criteria indicated by the to-be-zeroed bit field. This avoids excessive action of converting all blocks uniformly, thereby preventing unnecessary resource allocation while maintaining conversion effectiveness.
Solution Approach 2:
The to-be-zeroed bit field serves as a feedback mechanism that tracks which data blocks require conversion. This feedback information guides the conversion process to operate only on necessary blocks, preventing both data loss and unnecessary resource allocation by providing real-time status information about block conversion requirements.
Data Source
AI summary
System and method for converting disk format types of virtual disks in storage executes, in response to a request to convert a disk format type of a target virtual disk from a source disk format type to a destination disk format type, a conversion procedure on each data block of the target virtual disk that satisfies a predefined condition. The conversion procedure executed is based on the source and destination disk format types. The conversion procedure includes taking possession of a granular offset lock for a data block of the target virtual disk, performing a conversion operation on the data block of the target virtual disk only when the data block of the target virtual disk satisfies a required condition, and releasing the granular offset lock for the data block of the target virtual disk after the conversion operation on the data block has been performed.