HP StorageWorks 2000 Series Reference Manual page 212

To disable or enable a PHY:
In the Expander Controller Phy Detail panel, click the PHY's Disable or Enable
button.
When you disable a PHY, its button changes to Enable and its Status value changes
to DISABLED. When you enable a PHY, its button changes to Disable and its status
value changes to OK or another status.
You can change an expander's PHY Isolation setting to enable or disable fault
monitoring and isolation for all PHYs in that expander. If Disable is shown, the
setting is enabled; if Enable is shown, the setting is disabled. This setting is enabled
by default.
To change the PHY isolation setting for expander A or expander B:
In the Phy Isolation Details panel, click the Phy Isolation field's Disable or Enable
button.
When you disable PHY isolation, its button changes to Enable. When you enable
PHY isolation, its button changes to Disable.