A Unix server completes POST successfully. The server starts to boot but crashes and halts on a transport error. Which of the following components should a technician check FIRST?

A video card failure would produce display issues or a POST error code, not a transport error encountered after POST during OS loading.

A cooling fan malfunction typically triggers a thermal warning or protective shutdown, not a data transport error in the boot sequence.

Memory modules are tested during POST, which completed successfully, making a memory fault an unlikely cause of a post-POST transport error.

A transport error refers to a failure in the data transfer layer between the storage device and the host controller, such as SCSI, SATA, or SAS transport failures. Because POST completed successfully, basic hardware components like CPU and RAM passed initial checks, narrowing the fault to the storage subsystem. The technician should check the hard drive, its cables, and the storage controller as the first diagnostic step.