HP StorageWorks 2000 Series Reference Manual page 204

Reconstruction can take hours or days to complete, depending on the virtual
disk RAID level and size, drive speed, utility priority, and other processes running
on the storage system. You can stop reconstruction only by deleting the virtual disk.
When isolating data path faults, you must first isolate the fault to an internal data
path or an external data path. This will help to target your troubleshooting efforts.
Internal data paths include the following:
Controller to disk connectivity
Controller to controller connectivity
Controller ingress (incoming signals from drive enclosures)
Controller egress (outgoing signals to drive enclosures)
External data paths consist of the connections between the storage system and data
hosts.
To troubleshoot a data path using SMU, do the following:
Identify the fault as an internal or external data path fault using the steps in
"Determining Storage System Status and Verifying Faults" on page 197
Gather details about the fault
Review event logs
Replace the faulty component
A Physical Layer Interface (PHY) is an interface in a device used to connect to
other devices. The term refers to the physical layer of the Open Systems
Interconnect (OSI) basic reference model. The physical layer defines all of the
electrical and physical specifications for a device.
In a SAS architecture, each physical point-to-point connection is called a lane.
Every lane has a PHY at either end. Lanes are sometimes referred to as physical
links.
Fault isolation firmware monitors hardware PHYs for problems.