If Solaris Volume Manager takes a volume offline due to errors, unmount all file systems on the disk where the failure occurred.
Because each disk slice is independent, multiple file systems can be mounted on a single disk. If the software has encountered a failure, other slices on the same disk will likely experience failures soon. File systems that are mounted directly on disk slices do not have the protection of Solaris Volume Manager error handling. Leaving such file systems mounted can leave you vulnerable to crashing the system and losing data.
Minimize the amount of time you run with submirrors that are disabled or offline. During resynchronization and online backup intervals, the full protection of mirroring is gone.