Migration-Aware Load Balancing for Virtual Data Centers
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Solution Overview
Problem
Existing load balancing systems in virtual data centers are unaware of virtual machine (VM) migration states, leading to performance challenges such as increased memory copying, memory-related bookkeeping, and additional downtime during live migration, as they treat migrating VMs similarly to non-migrating ones, and struggle to respond to short resource spikes.
Innovation Solution
Implementing a notification mechanism that informs load balancing modules of upcoming VM migrations, allowing them to reduce the load on the migrating VM before migration, redistribute loads among other servers during migration, and increase the load on the VM after migration is complete, thereby minimizing performance degradation and migration downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If load balancers treat migrating VMs the same as non-migrating VMs, then the system is simple to operate, but performance degradation occurs during migration
Solution Approach 1:
The load balancer receives a migration notification before the actual migration occurs and proactively reduces the load on the migrating VM in advance. This preliminary action prevents performance degradation during migration by reducing new connection establishment before the migration process begins, while maintaining existing connections.
2Productivity
If load balancers continuously dispatch new connections to migrating VMs, then connection distribution is maintained, but memory copying increases during pre-copy phase
Solution Approach 1:
The load balancer reduces the quantity of new connections dispatched to the migrating VM before and during the migration process. This preliminary reduction in connection establishment minimizes the memory copying required during the pre-copy phase of migration, as fewer new connections need to be established on the destination host.
3Device complexity
If load balancers do not know about VM migration states, then the system is easier to implement, but migration downtime increases
Solution Approach 1:
The migration notification mechanism provides feedback to the load balancer about the migration state of VMs. This feedback enables the load balancer to adjust its behavior during migration by reducing load on migrating VMs, thereby minimizing migration downtime while adding only minimal complexity through the notification interface.
4Device complexity
If load balancers use passive probing to track web server status, then implementation is simple, but response time to resource spikes is delayed
Solution Approach 1:
Instead of passively probing for status changes after they occur, the system uses migration notifications to trigger load balancing actions in advance. This preliminary action allows the load balancer to respond immediately to migration events and adjust traffic distribution before resource spikes affect performance.
Data Source
AI summary
Embodiments perform migration-aware load balancing in virtual data centers. One or more load balancing modules in a host distribute data requests from clients to one or more servers implemented as virtual machines (VMs). The load balancing modules are notified of VM migration (e.g., live migration) prior to the VM migration and reduce the load on the VM to be migrated. After being notified of completion of VM migration, the load balancing modules increase the load on the migrated VM. Such migration notifications enable the load balancing modules to prevent or reduce performance degradation and migration duration, among other aspects.