You can use the fssnap command to create a snapshot of a file system. A snapshot is a file system's temporary image that is intended for backup operations.
When run, the fssnap command creates a virtual device and a backing-store file. You can back up the virtual device, which looks and acts like a real device, with any of the existing Solaris backup commands. The backing-store file is a bitmapped file that contains copies of pre-snapshot data that has been modified since the snapshot was taken.
See the System Administration Guide: Basic Administration and the man page, fssnap(1M), for more information.