When you use the ldm add-vdisk command to add a virtual disk to a domain, you can specify its device number by setting the id property.
# ldm add-vdisk [id=disk-id] disk-name volume-name@service-name ldom
Each virtual disk of a domain has a unique device number that is assigned when the domain is bound. If a virtual disk is added with an explicit device number (by setting the id property), the specified device number is used. Otherwise, the system automatically assigns the lowest device number available. In that case, the device number assigned depends on how virtual disks were added to the domain. The device number eventually assigned to a virtual disk is visible in the output of the ldm list-bindings command when a domain is bound.
When a domain with virtual disks is running the Solaris OS, each virtual disk appears in the domain as a c0dn disk device, where n is the device number of the virtual disk.
In the following example, the ldg1 domain has two virtual disks: rootdisk and pdisk. rootdisk has a device number of 0 (disk@0) and appears in the domain as the disk device c0d0. pdisk has a device number of 1 (disk@1) and appears in the domain as the disk device c0d1.
primary# ldm list-bindings ldg1 ... DISK NAME VOLUME TOUT DEVICE SERVER MPGROUP rootdisk dsk_nevada@primary-vds0 disk@0 primary pdisk c3t40d1@primary-vds0 disk@1 primary ...
If a device number is not explicitly assigned to a virtual disk, its device number can change when the domain is unbound and is later bound again. In that case, the device name assigned by the OS running in the domain can also change and break the existing configuration of the system. This might happen, for example, when a virtual disk is removed from the configuration of the domain.