Before formatting a device, ZFS first determines if the disk is in-use by ZFS or some other part of the operating system. If the disk is in use, you might see errors such as the following:
# zpool create tank c1t0d0 c1t1d0 invalid vdev specification use '-f' to override the following errors: /dev/dsk/c1t0d0s0 is currently mounted on /. Please see umount(1M). /dev/dsk/c1t0d0s1 is currently mounted on swap. Please see swap(1M). /dev/dsk/c1t1d0s0 is part of active ZFS pool zeepool. Please see zpool(1M).
The disk or one of its slices contains a file system that is currently mounted. To correct this error, use the umount command.
The disk contains a file system that is listed in the /etc/vfstab file, but the file system is not currently mounted. To correct this error, remove or comment out the line in the /etc/vfstab file.
The disk is in use as the dedicated dump device for the system. To correct this error, use the dumpadm command.
The disk or file is part of an active ZFS storage pool. To correct this error, use the zpool destroy command to destroy the other pool, if it is no longer needed. Or, use the zpool detach command to detach the disk from the other pool. You can only detach a disk from a mirrored storage pool.
The following in-use checks serve as helpful warnings and can be overridden by using the -f option to create the pool:
The disk contains a known file system, though it is not mounted and doesn't appear to be in use.
The disk is part of a Solaris Volume Manager volume.
The disk is in use as an alternate boot environment for Oracle Solaris Live Upgrade.
The disk is part of a storage pool that has been exported or manually removed from a system. In the latter case, the pool is reported as potentially active, as the disk might or might not be a network-attached drive in use by another system. Be cautious when overriding a potentially active pool.
The following example demonstrates how the -f option is used:
# zpool create tank c1t0d0 invalid vdev specification use '-f' to override the following errors: /dev/dsk/c1t0d0s0 contains a ufs filesystem. # zpool create -f tank c1t0d0
Ideally, correct the errors rather than use the -f option to override them.