Here is some more info
How to reload the st driver without rebooting Solaris 7 11/99 and above
http://seer.support.veritas.com/docs/245499.htm
Details:
The device management in Solaris is enhanced by using the devfsadmd daemon with Solaris 7 (Release 11/99) and newer major versions like Solaris 8. This daemon of capable of dynamically reconfiguring devices during boot process as well as in response to kernel event notifications.
The devfsadm located in /usr/sbin is the command form of devfsadmd. This replaces drvconfig (manages physical device tree /devices) and devlinks (manages logical devices in /dev). Also there is no need for the commands for specific device class type like /usr/sbin/tapes.
Thus, in order to re-create tape devices for VERITAS NetBackup after changing the /kernel/drv/st.conf file without rebooting the server, perform the following steps:
1. Shutdown NetBackup and media manager daemons.
2. Obtain the module id for st driver in kernel:
/usr/sbin/modinfo | grep SCSI
The module id is the first field in the line corresponding to SCSI tape driver.
3. Unload the st driver from kernel:
/usr/sbin/modunload -i
4. Use devfsadm to recreate the device nodes (in /devices) and device links (in /dev) for tape devices by running:
/usr/sbin/devfsadm -i st
OR
/usr/sbin/devfsadm -c tape
OR
If dangling logical links are present in /dev, cleanup can be enforced by running:
/usr/sbin/devfsadm -C -c tape
5. Reload the st driver:
/usr/sbin/modload st
6. Restart NetBackup and media manager daemons.
Related Documents:
187797: How to reload the SCSI tape (st) driver settings without doing a boot -r.