Volume Manager Driver I/O Fencing for Virtual Storage
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Solution Overview
Problem
Existing I/O fencing methods are limited to physical storage devices and do not apply to virtual storage devices, necessitating a solution to implement industry-standard I/O fencing methodologies for virtual machine clusters and virtual storage objects without requiring significant changes to software or hardware.
Innovation Solution
A volume manager driver reserves private regions in virtual storage objects to store metadata for I/O fencing, translating access requests to manage access according to I/O fencing standards like SCSI-3 PGR, allowing virtual machines to access virtual storage devices while maintaining data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SCSI-3 PGR based I/O fencing is implemented for physical storage devices, then data integrity is maintained through node isolation, but the solution cannot be applied to virtual storage devices
Solution Approach 1:
The patent creates a virtual copy of the physical I/O fencing mechanism by implementing SCSI-3 PGR compatible reservation keys and group reservation data structures in virtual storage objects. The volume manager driver translates virtual machine I/O fencing requests into standard SCSI-3 PGR commands, allowing virtual storage devices to use the same I/O fencing methodology as physical devices without requiring hardware modifications
Solution Approach 2:
The volume manager driver acts as an intermediary layer between virtual machines and physical storage devices. It translates virtual I/O fencing operations into standard SCSI-3 PGR commands, enabling virtual storage objects to participate in I/O fencing protocols designed for physical devices. This intermediary layer maintains compatibility with existing I/O fencing standards while extending functionality to virtual environments
2Reliability
If virtual storage devices use custom I/O fencing mechanisms, then I/O fencing capability is achieved, but significant changes to software and hardware are required
Solution Approach 1:
The patent makes the volume manager driver universal by enabling it to handle both virtual storage operations and I/O fencing operations through a single component. The driver implements SCSI-3 PGR compatible functionality within the virtual storage stack, allowing the same software component to manage both data I/O and fencing operations without requiring separate hardware or software systems
Solution Approach 2:
The patent replaces physical hardware-based I/O fencing mechanisms with software-based implementations in the volume manager driver. Instead of requiring specialized hardware for I/O fencing, the solution uses software to create and manage reservation keys, group reservation data, and preemption logic, thereby eliminating the need for significant hardware modifications while maintaining I/O fencing capability
Data Source
AI summary
A system, method, and medium for implementing I/O fencing in a virtual machine cluster sharing virtual storage objects. A volume manager driver receives access requests from virtual machines directed to a virtual storage object such as a volume. The volume manager driver then translates the access request to point to a storage device underlying the volume. The access request includes keys and/or other group reservation data required to implement an I/O fencing method so as to prevent access to shared data by malfunctioning or non-responsive virtual machines.