Virtual machine migration

A system, comprising:

• a client network comprising:
• a device that implements a server on the client network;
• and
• a storage system;
• a physical boot medium configured to be inserted in the device, wherein the boot medium stores program instructions for installing a migration appliance on the device upon a reboot of the device with the boot medium inserted in the device;
• wherein the migration appliance is configured to:
• receive, via a network connection over an intermediate network, a request from a migration initiator on a provider network for a boot sector for an operating system of the server;
• read the boot sector from a volume on the storage system that is logically attached to the server;
• convert the boot sector from a format used by the server to a format used by a virtual machine (VM) on a host device in the provider network;
• and
• send the converted boot sector to the migration initiator via the network connection, wherein the migration initiator boots the VM on the host device in the provider network according to the converted boot sector.

A method, comprising:

• installing a migration appliance on a server in a client network from a physical boot medium inserted in the server;
• reading, by the migration appliance, a boot sector of the server from a volume on a storage system of the client network that is logically attached to the server;
• converting, by the migration appliance, the boot sector from a format used by the server to a format used by a virtual machine (VM) on a host device in a provider network;
• and
• sending the converted boot sector to the provider network via a network connection over an intermediate network.

One or more non-transitory computer-readable storage media storing program instructions that when executed on or across one or more processors in a client network implement a migration appliance configured to:

• read a boot sector for an operating system of a server from a volume on a storage system of the client network that is logically attached to the server;
• and
• send the boot sector to a provider network via a network connection over an intermediate network, wherein a virtual machine (VM) is booted on a host device in the provider network according to the boot sector;
• wherein the server is a physical device on the client network, and wherein the migration appliance is booted on the server from the storage media.