Host Alignment Module for Virtual Disk Track Alignment
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Solution Overview
Problem
Virtual machine partitions are often misaligned with underlying physical disk tracks, leading to diminished I/O performance due to data being read or written across track boundaries, which existing alignment mechanisms fail to address for guest machines.
Innovation Solution
A host alignment module determines a target starting location for guest partitions within virtual machines to ensure alignment with physical disk tracks, translating virtual hard disk addresses into physical addresses and adjusting them if necessary to align with disk tracks, thereby preventing overlap and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If guest partitions are created without alignment adjustment, then partition creation is simple and fast, but I/O performance deteriorates due to track boundary overlaps
Solution Approach 1:
The host alignment module performs alignment determination and address translation before the guest partition is actually created. By calculating the target starting location in advance and providing it to the guest alignment module, the system ensures proper alignment without adding complexity to the partition creation process itself. The alignment adjustments are made preliminarily, so when the guest writes data, the partitions are already optimally positioned on physical disk tracks.
2Manufacturing precision
If virtual hard disk addresses are used directly without translation, then address mapping is simple, but physical track alignment cannot be achieved
Solution Approach 1:
The host alignment module acts as an intermediary between the guest alignment module and the physical hard disk. It receives virtual hard disk addresses from the guest, translates them into physical hard disk addresses, determines whether alignment is needed, and returns the appropriate target starting location. This intermediary layer handles the complexity of address translation and alignment determination, while the guest system remains unaware of the underlying physical disk structure.
Data Source
AI summary
In response to a request received from a guest alignment module, host alignment module determines a target starting location in a virtual hard disk to which the beginning of a guest partition of a virtual machine is written. Host alignment module translates a guest partition's virtual hard disk address into a physical hard disk address and determines whether the physical hard disk address is track aligned with disk tracks of the physical hard disk. If the physical hard disk address is not track aligned, host alignment module determines a new track aligned physical hard disk address as the target starting location. If the physical hard disk address is track aligned, the same physical hard disk address is used as the target starting location. The target starting location is returned to the guest alignment module as a new virtual hard disk address.