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docs: Add documentation for cross-host TCP live migration

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Updated the live migration documentation to include instructions for
performing cross-host live migrations over TCP connections.

Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
This commit is contained in:
Jinrong Liang 2024-12-02 19:45:48 +08:00 committed by Rob Bradford
parent 909e1bc3f0
commit b9163bf431
1 changed files with 64 additions and 11 deletions
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docs/live_migration.md
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@ -1,7 +1,7 @@
# Live Migration
This document gives two examples of how to use the live migration
support in Cloud Hypervisor:
This document gives examples of how to use the live migration support
in Cloud Hypervisor:
1. local migration - migrating a VM from one Cloud Hypervisor instance to another on the same machine;
1. remote migration - migrating a VM between two machines;
@ -50,14 +50,11 @@ In this example, we will migrate a VM from one machine (`src`) to
another (`dst`) across the network. To keep it simple, we will use a
minimal VM setup without storage.
Because Cloud Hypervisor does not natively support migrating via TCP
connections, we will tunnel traffic through `socat`.
### Preparation
Make sure that `src` and `dst` can reach each other via the
network. You should be able to ping each machine. Also each machine
should have an open TCP port. For this example we assume port 6000.
should have an open TCP port.
You will need a kernel and initramfs for a minimal Linux system. For
this example, we will use the Debian netboot image.
@ -75,7 +72,11 @@ src $ curl $DEBIAN/initrd.gz > /var/images/initrd
Repeat the above steps on the destination host.
### Starting the Receiver VM
### Unix Socket Migration
If Unix socket is selected for migration, we can tunnel traffic through "socat".
#### Starting the Receiver VM
On the receiver side, we prepare an empty VM:
@ -92,10 +93,10 @@ dst $ ch-remote --api-socket=/tmp/api receive-migration unix:/tmp/sock
In yet another terminal, forward TCP connections to the Unix domain socket:
```console
dst $ socat TCP-LISTEN:6000,reuseaddr UNIX-CLIENT:/tmp/sock
dst $ socat TCP-LISTEN:{port},reuseaddr UNIX-CLIENT:/tmp/sock
```
### Starting the Sender VM
#### Starting the Sender VM
Let's start the VM on the source machine:
@ -111,14 +112,16 @@ src $ cloud-hypervisor \
After a few seconds the VM should be up and you can interact with it.
### Performing the Migration
#### Performing the Migration
First, we start `socat`:
```console
src $ socat UNIX-LISTEN:/tmp/sock,reuseaddr TCP:dst:6000
src $ socat UNIX-LISTEN:/tmp/sock,reuseaddr TCP:{dst}:{port}
```
> Replace {dst}:{port} with the actual IP address and port of your destination host.
Then we kick-off the migration itself:
```console
@ -127,3 +130,53 @@ src $ ch-remote --api-socket=/tmp/api send-migration unix:/tmp/sock
When the above commands completed, the VM should be successfully
migrated to the destination machine without interrupting the workload.
### TCP Socket Migration
If TCP socket is selected for migration, we need to consider migrating
in a trusted network.
#### Starting the Receiver VM
On the receiver side, we prepare an empty VM:
```console
dst $ cloud-hypervisor --api-socket /tmp/api
```
In a different terminal, prepare to receive the migration:
```console
dst $ ch-remote --api-socket=/tmp/api receive-migration tcp:0.0.0.0:{port}
```
#### Starting the Sender VM
Let's start the VM on the source machine:
```console
src $ cloud-hypervisor \
--serial tty --console off \
--cpus boot=2 --memory size=4G \
--kernel /var/images/linux \
--initramfs /var/images/initrd \
--cmdline "console=ttyS0" \
--api-socket /tmp/api
```
After a few seconds the VM should be up and you can interact with it.
#### Performing the Migration
Initiate the Migration over TCP:
```console
src $ ch-remote --api-socket=/tmp/api send-migration tcp:{dst}:{port}
```
> Replace {dst}:{port} with the actual IP address and port of your destination host.
After completing the above commands, the source VM will be migrated to
the destination host and continue running there. The source VM instance
will terminate normally. All ongoing processes and connections within
the VM should remain intact after the migration.