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 a device to a running subsystem, said host bus adaptor comprising:

• a control component for encapsulating said process of attachment of a device to a running subsystem;
• a disabling component for disabling a path interface;
• a testing component for testing for the presence of a usable data path across at least one further path interface;
• and
• an enabling component for enabling said at least one further path interface to accept communication with said device responsive to a positive outcome from said testing component, wherein said control component is adapted to permit operation after attachment of said device only if full redundancy is retained.

An enclosure comprising one or more disk drives wherein the enclosure is configured for reducing incidence of errors in a redundant path system during a process of attachment of a device to a running subsystem, said enclosure comprising:

• a control component for encapsulating said process of attachment of a device to a running subsystem;
• a disabling component for disabling a path interface;
• a testing component for testing for the presence of a usable data path across at least one further path interface;
• an enabling component for enabling said at least one further path interface to accept communication with said device responsive to a positive outcome from said testing component, wherein said control component is adapted to permit operation after attachment of said device only if full redundancy is retained;
• a re-enabling component for re-enabling any said path interface or further path interface;
• 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 a device to a running subsystem, the system comprising:

• a host bus adaptor;
• an enclosure comprising one or more disk drives connected to an interface on said enclosure by a cable;
• a cable connecting said host bus adaptor to said interface;
• a control component for encapsulating said process of attachment of a device to a running subsystem;
• a disabling component for disabling a path interface;
• a testing component for testing for the presence of a usable data path across at least one further path interface;
• and
• an enabling component for enabling said at least one further path interface to accept communication with said device responsive to a positive outcome from said testing component, wherein said control component is adapted to permit operation after attachment of said device only if full redundancy is retained.

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

• encapsulating, by a control component, said process of attachment of a device to a running subsystem;
• disabling a path interface;
• testing for the presence of a usable data path across at least one further path interface;
• and
• enabling said at least one further path interface to accept communication with said device responsive to a positive outcome from said testing component;
• wherein said control component is adapted to permit operation after attachment of said device only if full redundancy is retained.

A computer program product comprising computer program code to, when loaded into a computer system and executed thereon, cause said computer system to reduce incidence of errors in a redundant path system during a process of attachment of a device to a running subsystem, by performing the steps of:

• encapsulating, by a control component, said process of attachment of a device to a running subsystem;
• disabling a path interface;
• testing for the presence of a usable data path across at least one further path interface;
• and
• enabling said at least one further path interface to accept communication with said device responsive to a positive outcome from said testing component;
• wherein said control component is adapted to permit operation after attachment of said device only if full redundancy is retained.

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

• means for encapsulating, by a control component, said process of attachment of a device to a running subsystem;
• means for disabling a path interface;
• means for testing for the presence of a usable data path across at least one further path interface;
• means for enabling said at least one further path interface to accept communication with said device responsive to a positive outcome from said testing component, wherein said control component is adapted to permit operation after attachment of said device only if full redundancy is retained;
• means for re-enabling any said path interface or further path interface;
• 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.