Method and apparatus for improved error avoidance in a redundant data path system

A host bus adaptor configured to reduce incidence of errors in a redundant path system during a process of attachment of an enclosure to a running subsystem, said host bus adaptor comprising:

• a control component for encapsulating said process of attachment of said enclosure to said running subsystem via a first loop comprising a first FC-AL cable connected between a first FC-AL interface connection of said enclosure and a first FC-AL interface connection of said subsystem and a second loop comprising a second FC-AL cable connected between a second FC-AL interface connection of said enclosure and a second FC-AL interface connection of said subsystem;
• a disabling component for disabling said first interface connection of said subsystem and said second interface connection of said subsystem as unused connections;
• a re-enabling component enabling said first interface connection of said subsystem;
• a testing component for testing for the presence of a usable data path across said first interface connection of said subsystem to said enclosure;
• said re-enabling component re-enabling said second interface connection of said subsystem;
• said testing component testing for the presence of a usable data path across said first interface connection and said second interface connection of said subsystem to said enclosure;
• an enabling component enabling said first interface connection and said second interface connection of said subsystem to accept communication with said enclosure responsive to a positive outcome from said testing component, wherein said control component permits operation after attachment of said enclosure only if full redundancy is retained.

An enclosure for reducing incidence of errors in a redundant path system during a process of attachment of said enclosure to a running subsystem, said enclosure comprising:

• a control component for encapsulating said process of attachment of said enclosure to said running subsystem via a first loop comprising a first FC-AL cable connected between a first FC-AL interface connection of said enclosure and a first FC-AL interface connection of said subsystem and a second loop comprising a second FC-AL cable connected between a second FC-AL interface connection of said enclosure and a second FC-AL interface connection of said subsystem;
• a disabling component for disabling said first interface connection of said subsystem and said second interface connection of said subsystem as unused connections;
• a re-enabling component enabling said first interface connection of said subsystem;
• a testing component for testing for the presence of a usable data path across said first interface connection of said subsystem to said enclosure;
• said re-enabling component re-enabling said second interface connection of said subsystem;
• said testing component testing for the presence of a usable data path across said first interface connection and said second interface connection of said subsystem to said enclosure;
• an enabling component for enabling said first interface connection and said second interface connection of said subsystem to accept communication with said enclosure responsive to a positive outcome from said testing component, component, wherein said control component permits operation after attachment of said enclosure only if full redundancy is retained;
• an operator warning component to warn an operator that an expansion of said usable data path cannot be successful responsive to a negative result from said testing component;
• and
• a termination component for terminating said attachment process responsive to a negative result from said testing component.

A system for reducing incidence of errors in a redundant path system during a process of attachment of an enclosure to a running subsystem, the system comprising:

• a subsystem comprising a first FC-AL interface connection and a second FC-AL interface connection;
• an enclosure comprising one or more disk drives connected to a first FC-AL interface connection and a second FC-AL interface connection on said enclosure;
• a first FC-AL cable connecting said first interface connection of said subsystem to said first interface connection of said enclosure;
• a second FC-AL cable connecting said second interface connection of said subsystem to said second interface connection of said enclosure;
• a control component for encapsulating said process of attachment of said enclosure enclosure to said subsystem via a first loop comprising said first cable connected between said first interface connection of said enclosure and said first interface connection of said subsystem and a second loop comprising said second cable connected between said second interface connection of said enclosure and a second interface connection of said subsystem;
• a disabling component for disabling said first interface connection of said subsystem and said second interface connection of said subsystem as unused connections;
• a re-enabling component enabling said first interface connection of said subsystem;
• a testing component for testing for the presence of a usable data path across said first interface connection of said subsystem to said enclosure;
• said re-enabling component re-enabling said second interface connection of said subsystem;
• said testing component testing for the presence of a usable data path across said first interface connection and said second interface connection of said subsystem to said enclosure;
• and
• an enabling component for enabling said first interface connection and said second second interface connection of said subsystem to accept communication with said enclosure responsive to a positive outcome from said testing component, wherein said control component permits operation after attachment of said enclosure only if full redundancy is retained.

A method for reducing incidence of errors in a redundant path system during a process of attachment of an enclosure to a running subsystem, comprising the steps of:

• encapsulating, by a control component, said process of attachment of said enclosure to said running subsystem via a first loop comprising a first FC-AL cable connected between a first FC-AL interface connection of said enclosure and a first FC-AL interface connection of said subsystem and a second loop comprising a second FC-AL cable connected between a second FC-AL interface connection of said enclosure and a second FC-AL interface connection of said subsystem;
• disabling, by use of a controller, said first interface connection of said subsystem and said second interface connection of said subsystem as unused connections;
• enabling, by use of said controller, said first interface connection of said subsystem;
• testing, by use of said controller, for the presence of a usable data path across said first interface connection of said subsystem to said enclosure;
• re-enabling, by use of said controller, said second interface connection of said subsystem;
• testing, by use of said controller, for the presence of a usable data path across said first interface connection and said second interface connection of said subsystem to said enclosure;
• and
• enabling, by use of said controller, said first interface connection and said second interface connection of said subsystem to accept communication with said enclosure responsive to a positive outcome from said testing component;
• wherein said control component permits operation after attachment of said enclosure only if full redundancy is retained.

A storage medium storing program instructions executed by a computer system to reduce incidence of errors in a redundant path system during a process of attachment of an enclosure to a running subsystem by performing the steps of:

• encapsulating, by a control component, said process of attachment of said enclosure to said running subsystem via a first loop comprising a first FC-AL cable connected between a first FC-AL interface connection of said enclosure and a first FC-AL interface connection of said subsystem and a second loop comprising a second FC-AL cable connected between a second FC-AL interface connection of said enclosure and a second FC-AL interface connection of said subsystem;
• disabling said first interface connection of said subsystem and said second interface connection of said subsystem as unused connections;
• enabling, by use of said controller, said first interface connection of said subsystem:
• testing for the presence of a usable data path across said first interface connection of said subsystem to said enclosure;
• re-enabling said second interface connection of said subsystem;
• testing for the presence of a usable data path across said first interface connection and said second interface connection of said subsystem to said enclosure;
• and
• enabling said first interface connection and said second interface connection of said subsystem to accept communication with said enclosure responsive to a positive outcome from said testing component;
• wherein said control component permits operation after attachment of said enclosure only if full redundancy is retained.

An apparatus for reducing incidence of errors in a redundant path system during a process of attachment of an enclosure to a running subsystem, the apparatus comprising:

• means for encapsulating, by a control component, said process of attachment of said enclosure to said running subsystem via a first loop comprising a first FC-AL cable connected between a first FC-AL interface connection of said enclosure and a first FC-AL interface connection of said subsystem and a second loop comprising a second FC-AL cable connected between a second FC-AL interface connection of said enclosure and a second FC-AL interface connection of said subsystem;
• means for disabling said first interface connection of said subsystem and said second interface connection of said subsystem as unused connections;
• means for enabling said first interface connection of said subsystem;
• means for testing for the presence of a usable data path across said first interface connection of said subsystem to said enclosure;
• means for re-enabling said second interface connection of said subsystem;
• the testing means further testing for the presence of a usable data path across said first interface connection and said second interface connection of said subsystem to said enclosure;
• means for enabling said first interface connection and said second interface connection of said subsystem to accept communication with said enclosure responsive to a positive outcome from said testing component, wherein said control component permits operation after attachment of said enclosure only if full redundancy is retained;
• means for warning an operator that an expansion of said usable data path cannot be successful responsive to a negative result from said step of testing;
• and
• means for terminating an attachment process responsive to a negative result from said step of testing.