Windows Dynamic Disk (LDM) migration issue

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Windows VMs with an LDM system volume are supported. Everything about this migration path — prerequisites, what vJailbreak does, the cutover, and troubleshooting — is documented in one place: Windows Dynamic Disk (LDM) Migration.

Why LDM needs a different path

LDM (Logical Disk Manager) is Windows’ volume manager for “dynamic disks”. It is conceptually similar to Linux LVM, but it stores its volume metadata in a private database at the end of each disk rather than in a standard partition table.

virt-v2v converts a guest by inspecting it with libguestfs, reading the SYSTEM and SOFTWARE registry hives with Hivex, and writing VirtIO drivers and registry changes back into the offline filesystem. When the Windows system volume is an LDM volume, libguestfs cannot reliably assemble it, so inspection fails before conversion can start.

Rather than requiring the disk to be converted to basic beforehand, vJailbreak skips conversion for these guests and brings the VM up on an emulated SATA controller, which Windows can boot without VirtIO drivers. A temporary virtio temporary disk lets Windows install the viostor driver itself, and the migration then waits at the LDM Boot Verification phase for you to move the root disk to virtio.

Caution

Only the system volume matters. If just the data disks are dynamic, the VM migrates normally and no special handling is needed.

Converting to basic disks is no longer required

Earlier versions of this guide recommended running diskpart → convert basic on the source VM before migrating. That is no longer necessary, and convert basic requires an empty disk in any case. Follow the LDM migration guide instead.