Based on your description, this issue is most likely triggered under high I/O load, rather than a random crash. Especially the system becoming unresponsive during large file transfers, followed by storage pool synchronization after a restart, usually indicates instability in the underlying disks or RAID.
To further pinpoint the cause, we suggest you assist in checking the following:
Hard Drive Health Status (Very Important)
Please check the SMART information for all hard drives, paying particular attention to the following metrics:
Reallocated sectors
Pending sectors
CRC errors
Even if only one hard drive is faulty, high load can cause the system to freeze.
You may enable debug mode in TOS desktop>top dock bar>"Support and Help", when the issue occurs again, you may enter TOS by hard restart and generate debug logs, send to support email for us to further analyze why it freezes.
Synchronization occurs after each reboot, usually indicating that the RAID has detected data inconsistency, which may be caused by a brief disconnection of a hard drive during operation.
Resource Usage During Transfer
It is recommended to observe the system's CPU, memory, and I/O usage during large file transfers to determine if there are resource bottlenecks or system overload.