A master device is a slice or metadevice that contains the file system that is being logged. Logging begins automatically when the trans metadevice is mounted, provided the trans metadevice has a logging device. The master device can contain an existing UFS file system (because creating a trans metadevice does not alter the master device), or you can create a file system on the trans metadevice later. Likewise, clearing a trans metadevice leaves the UFS file system on the master device intact.
A logging device is a slice or metadevice that contains the log. A logging device can be shared by several trans metadevices. The log is a sequence of records, each of which describes a change to a file system.
A trans metadevice has the same naming conventions as other metadevices: /dev/md/dsk/d0, d1 ...,d2, and so forth. (For more information on metadevice naming conventions, see Table 1-4.)