In the case of a catastrophic failure, the X8 Accelerator may enter a read-only mode in order to preserve customer data from further corruption. This read-only mode will be logged in the system log (/var/log/messages).
Any operating system-cached data not yet written to the card will not be able to be written because of this. In the case of umount (unmount), the operating system may freeze during the umount operation as it attempts and re-attempts to write the cached data back to the drive.
If you experience such a failure, please contact Seagate Support for debugging and possible warranty service.