VM Memory Replication via Local Data Copying
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Solution Overview
Problem
The existing live migration technique for virtual machines generates excessive network traffic and inefficiencies when replicating memory data between hosts, particularly affecting network performance during large data transfers like those involving databases.
Innovation Solution
The proposed solution involves using checksums and dirty page tracking to determine which memory data is locally available on other hosts, allowing the replication service to copy data from these hosts instead of transferring it from the source host, thereby reducing network traffic. This includes maintaining checksums for memory chunks, tracking dirty pages, and selecting hosts based on local availability and network proximity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all memory data is transferred from source host to destination host during replication, then complete memory state replication is achieved, but network traffic becomes excessive and network performance deteriorates
Solution Approach 1:
The patent extracts only the necessary memory pages (dirty pages) that have been modified since the last replication, rather than transferring all memory data. The hypervisor identifies and selects only those pages that contain changes, excluding unchanged pages from the transfer process, thereby reducing network traffic while maintaining replication completeness.
Solution Approach 2:
The patent applies partial action by transferring only a subset of memory pages (those marked as dirty) rather than the complete memory set. The dirty page tracking mechanism enables selective replication of only the necessary portion of memory data, optimizing network bandwidth usage while ensuring all changes are captured.
2Adaptability or versatility
If memory data is transferred over the network during live migration, then the virtual machine can be moved between hosts, but network performance is negatively affected due to excessive data transfer
Solution Approach 1:
The patent performs preliminary action by pre-identifying dirty pages through tracking mechanisms before the actual migration transfer. The hypervisor continuously monitors and marks modified pages in advance, so that during live migration, only the pre-identified necessary pages are transferred, reducing the impact on network performance while enabling seamless VM mobility.
3Loss of energy
If checksums are calculated and compared for all memory chunks to determine local availability, then data duplication is minimized, but processing overhead increases
Solution Approach 1:
The patent applies partial action by calculating checksums only for identified dirty pages rather than all memory chunks. The dirty page tracking mechanism narrows down the scope of checksum calculation to only those pages that have been modified, reducing processing overhead while still enabling effective detection of data duplication and optimization of replication operations.
Data Source
AI summary
Technologies are described herein for reducing network traffic when replicating memory data across hosts. The memory data stored in a main memory of the host computer is replicated to a main memory of a second host computer. Memory data from the local data storage of the second host computer and other hosts computers that is a duplicate of memory data from the main memory is identified. Instead of sending the memory data from the main memory that is duplicated, the duplicated memory is copied from the local storage of the second computer or from one or more of the other computers to the main memory of the second host computer.