Log in to the S5100 OSM, and view the utilization rates of the read/write cache and the mirroring write cache in the cache information of the service view. If the utilization rates are displayed as zero, service I/Os are deactivated.
If the services are essentially continuous writes and the display of the cache utilization remains zero for a long time, the services are probably interrupted.
If front-end services are running, the S5100 processes I/Os that can be traced from real-time cache statistics.
Monitor read/write operations on hard disks onsite to check whether I/Os are sent to storage devices.