live migration of virtual machines
DESCRIPTION
Live Migration of Virtual Machines. Presented by: Edward Armstrong University of Guelph. Overview. Problem Description Solutions Strengths and Weaknesses Results. Migrating an OS - Complexity. Migrating an OS – Timescale. Considerations. Both machines must be active at the same time. - PowerPoint PPT PresentationTRANSCRIPT
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Live Migration of Virtual MachinesPresented by:Edward ArmstrongUniversity of Guelph
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OverviewProblem DescriptionSolutionsStrengths and WeaknessesResults
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Migrating an OS - Complexity
•Same machine.•Hibernating a laptop.
Trivial•Same Hardware, different
Machine.•Changing cluster nodes.Moderat
e
•Different hardware.Complex
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Migrating an OS – Timescale
•Requires only long term storage to be migrated.•Loses all process state information.•Driver reloading solves hardware problems.
Reboot
•Typically performed on the same machine.•Requires long term storage.•Loses external connection information, ie. network
status.Hibernation
•Hibernation in short term storage (RAM).•Typically used to maintain a low power state.Suspend
•Processes are not implicitly frozen.•Differences in hardware create problems.•Solved by using virtual machines.Live
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ConsiderationsBoth machines must be active at
the same time.Migration of active live services.Total migration time.Resource contention.
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Migrating memory
Push
PausePull
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Memory - Pure stop and copy.
Pros◦ Simplicity.◦ Consistency.
Cons◦ Downtime proportional to
memory.◦ Unacceptable for live services.
Push
PausePull
Source Machine Target Machine
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Memory - On demand migration.Pros
◦ Shorter downtime.◦ Consistency.
Cons◦ Longer migration time.
Push
PausePull
Target MachineSource Machine
Page fault request
Send page
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Memory - Pre copy migration.
Pros◦ Copy low fault pages quickly.◦ Works well for live processes.
Cons◦ Large number of faults for
busy memory.
Push
PausePull
Target MachineSource Machine
Live page fault
Iterative push
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Network and disk resources.Unique to an OS instance.Ordering of resources are non-
determinsitic.Need to maintain open network
connections.
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Resolving network connections with an ARP* response.
Source MachineNo Address
Target Machine192.168.0.102
LAN
*ARP: Address Resolution Protocol
Packets
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Resolving network connections with an ARP* response.
Source MachineNo Address
Target Machine192.168.0.102
LAN
*ARP: Address Resolution Protocol
Unsolicited ARP reply
Packets
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Resolving network connections with an ARP* response.
Source Machine192.168.0.102
Target MachineNo Address
LAN
*ARP: Address Resolution Protocol
Packets
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Network resources.Pros
◦Handled by external devices.◦Similar scheme can be used to
migrate disk services (not covered in paper).
Cons◦Small amount of packet loss.◦Requires a LAN with unsolicited ARP
responses enabled.
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Design OverviewPre-
MigrationReservati
on Pre-Copy
Stop and CopyCommitActivate
Source Machine Target MachineSelect a new target machine
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Design OverviewPre-
MigrationReservati
on Pre-Copy
Stop and CopyCommitActivate
Source Machine Target Machine
Confirm available resources on target.Failure means VM continues to run on source.
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Design OverviewPre-
MigrationReservati
on Pre-Copy
Stop and CopyCommitActivate
Source Machine Target Machine
Transfer memory.Retransmit memory used during transfer.
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Design OverviewPre-
MigrationReservati
on Pre-Copy
Stop and CopyCommitActivate
Source Machine Target Machine
Halt source to redirect network trafficand transfer CPU state.
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Design OverviewPre-
MigrationReservati
on Pre-Copy
Stop and CopyCommitActivate
Source Machine Target MachineVerify transfer complete.Disable source.
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Design OverviewPre-
MigrationReservati
on Pre-Copy
Stop and CopyCommitActivate
Source Machine Target Machine
Activate target machine
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Summary of DesignAt all times there is at least one
consistent image available.Minimized down time.Not a fast process overall.Requires tuning.Requires certain hardware.
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Performance – Dirty Pages.
8 second granularity, used to decide which pages make for good pre-migration.
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Performance
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Performance
1- 4 pre-copy iterations
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Performance
1- 4 pre-copy iterations
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Performance
1- 4 pre-copy iterations
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Thank You