On-line disk array reconfiguration

A method of reconfiguring a disk array while maintaining data stored in the disk array accessible by other host requests, wherein a source logical volume is reconfigured to a destination logical volume, the source and destination logical volumes being defined on the disk array, and wherein the disk array is coupled to a disk controller having a posting memory the method comprising the steps of:

• a) moving one transfer unit of data from the source logical volume to the posting memory,
• b) moving said transfer unit of data from the posting memory to the destination logical volume;
• c) repeating steps (a)-(b) until all data in the source logical volume have been moved to the destination logical volume, and
• d) if a host request is asserted for specified blocks of data, determining if said specified blocks are located in said source logical volume or said destination logical volume and pointing said host request to the appropriate one of said source and destination logical volumes,
• wherein the source logical volume has a first stripe size and the destination logical volume has a second stripe size, and wherein said transfer unit has a size equal to the least common denominator of said first and second stripe sizes.

A method of reconfiguring a disk array while maintaining data stored in the disk array accessible by other host requests, wherein a source logical volume is reconfigured to a destination logical volume, the source and destination logical volumes being defined on the disk array, and wherein the disk array is coupled to a disk controller having a posting memory, the method comprising the steps of:

• a) moving one transfer unit of data from the source logical volume to the posting memory;
• b) moving said transfer unit of data from the posting memory to the destination logical volume;
• c) repeating steps (a)-(b) until all data in the source logical volume have been moved to the destination logical volume;
• and
• d) if a host request is asserted for specified blocks of data, determining if said specified blocks are located in said source logical volume or said destination logical volume and pointing said host request to the appropriate one of said source and destination logical volumes,
• wherein the posting memory further contains a configuration area to store progress information associated with the expand method, and wherein the posting memory is battery-backed, the method further comprising the steps of:
• retrieving said progress information from said configuration area if a power failure interrupted the reconfiguration method;
• and
• restarting the reconfiguration method based on said progress information.

A disk controller for transferring data between a disk array and a host computer, the disk controller comprising:

• a bus;
• a posting memory coupled to said bus;
• means coupled to said bus for reconfiguring the disk array, wherein a source logical volume is reconfigured to a destination logical volume, said source and destination logical volumes being defined on the disk array, and said reconfiguring means including:
• first means coupled to said bus for moving data from said source logical volume to said posting memory, said data being moved one transfer unit at a time;
• second means coupled to said bus for moving said source logical volume data from said posting memory to said destination logical volume after one transfer unit of data has been moved to said posting memory;
• means coupled to said bus for receiving a host request from the host computer, said host request asserted for specified blocks of data;
• means coupled to said receiving means for determining if said requested blocks are located in said source logical volume or said destination logical volume;
• and
• means coupled to said determining means for pointing said host request to the appropriate one of said source and destination logical volumes,
• wherein the transfer unit of data is a stripe not presently being configured of a data block undergoing reconfiguration.

A disk controller for transferring data between a disk array and a host computer, the disk controller comprising:

• a bus;
• a posting memory coupled to said bus;
• means coupled to said bus for reconfiguring the disk array, wherein a source logical volume is reconfigured to a destination logical volume, said source and destination logical volumes being defined on the disk array, and said reconfiguring means including:
• first means coupled to said bus for moving data from said source logical volume to said posting memory, said data being moved one transfer unit at a time;
• second means coupled to said bus for moving said source logical volume data from said posting memory to said destination logical volume after one transfer unit of data has been moved to said posting memory;
• means coupled to said bus for receiving a host request from the host computer, said host request asserted for specified blocks of data;
• means coupled to said receiving means for determining if said requested blocks are located in said source logical volume or said destination logical volume;
• and
• means coupled to said determining means for pointing said host request to the appropriate one of said source and destination logical volumes,
• wherein said source logical volume has a first stripe size and said destination logical volume has a second stripe size, and wherein said transfer unit has a size equal to the least common denominator of said first and second stripe sizes.

A disk controller for transferring data between a disk array and a host computer, the disk controller comprising:

• a bus;
• a posting memory coupled to said bus
• means coupled to said bus for reconfiguring the disk array, wherein a source logical volume is reconfigured to a destination logical volume, said source and destination logical volumes being defined on the disk array, and said reconfiguring means including:
• first means coupled to said bus for moving data from said source logical volume to said posting memory, said data being moved one transfer unit at a time;
• second means coupled to said bus for moving said source logical volume data from said posting memory to said destination logical volume after one transfer unit of data has been moved to said posting memory;
• means coupled to said bus for receiving a host request from the host computer, said host request asserted for specified blocks of data;
• means coupled to said receiving means for determining if said requested blocks are located in said source logical volume or said destination logical volume;
• and
• means coupled to said determining means for pointing said host request to the appropriate one of said source and destination logical volumes,
• wherein said reconfiguration means further includes:
• means coupled to said bus for receiving reconfigure requests from the host computer;
• and
• a queue coupled to said reconfigure request receiving means, said reconfigure requests being entered into said queue, wherein said reconfiguration means is activated if a reconfigure request is pending in said queue.

A disk controller for transferring data between a disk array and a host computer, the disk controller comprising:

• a bus;
• a posting memory coupled to said bus;
• reconfiguring processor logic coupled to said bus for reconfiguring the disk array, wherein a source logical volume is reconfigured to a destination logical volume, said source and destination logical volumes being defined on the disk array, and said reconfiguring processor logic including:
• first data transfer logic coupled to said bus for moving data from said source logical volume to said posting memory, said data being moved one transfer unit at a time;
• second data transfer logic coupled to said bus for moving said source logical volume data from said posting memory to said destination logical volume after one transfer unit of data has been moved to said posting memory;
• host request receiving logic coupled to said bus for receiving a host request from the host computer, said host request asserted for specified blocks of data;
• determining logic coupled to said host request receiving logic for determining if said requested blocks are located in said source logical volume or said destination logical volume;
• and
• indicator logic coupled to said determining logic for pointing said host request to the appropriate one of said source and destination logical volumes,
• wherein the transfer unit of data is a stripe of a data block undergoing reconfiguration whereby the stripe is not presently being reconfigured.

A disk controller for transferring data between a disk array and a host computer the disk controller comprising:

• a bus;
• a posting memory coupled to said bus;
• reconfiguring processor logic coupled to said bus for reconfiguring the disk array, wherein a source logical volume is reconfigured to a destination logical volume, said source and destination logical volumes being defined on the disk array, and said reconfiguring processor logic including:
• first data transfer logic coupled to said bus for moving data from said source logical volume to said posting memory, said data being moved one transfer unit at a time;
• second data transfer logic coupled to said bus for moving said source logical volume data from said posting memory to said destination logical volume after one transfer unit of data has been moved to said posting memory;
• host request receiving logic coupled to said bus for receiving a host request from the host computer, said host request asserted for specified blocks of data;
• determining logic coupled to said host request receiving logic for determining if said requested blocks are located in said source logical volume or said destination logical volume;
• and
• indicator logic coupled to said determining logic for pointing said host request to the appropriate one of said source and destination logical volumes,
• wherein said source logical volume has a first stripe size and said destination logical volume has a second stripe size, and wherein said transfer unit has a size equal to the least common denominator of said first and second stripe sizes;
• and wherein the transfer unit of data is a stripe not presently being reconfigured.

A disk controller for transferring data between a disk array and a host computer, the disk controller comprising:

• a bus;
• a posting memory coupled to said bus;
• reconfiguring processor logic coupled to said bus for reconfiguring the disk array, wherein a source logical volume is reconfigured to a destination logical volume, said source and destination logical volumes being defined on the disk array, and said reconfiguring processor logic including:
• first data transfer logic coupled to said bus for moving data from said source logical volume to said posting memory, said data being moved one transfer unit at a time;
• second data transfer logic coupled to said bus for moving said source logical volume data from said posting memory to said destination logical volume after one transfer unit of data has been moved to said posting memory;
• host request receiving logic coupled to said bus for receiving a host request from the host computer said host request asserted for specified blocks of data;
• determining logic coupled to said host request receiving logic for determining if said requested blocks are located in said source logical volume or said destination logical volume;
• and
• indicator logic coupled to said determining logic for pointing said host request to the appropriate one of said source and destination logical volumes,
• wherein said reconfiguring processor logic further includes:
• reconfigure request receiving logic coupled to said bus for receiving reconfigure requests from the host computer;
• and
• a queue coupled to said reconfigure request receiving logic, said reconfigure requests being entered into said queue, wherein said reconfiguring processor logic is activated if a reconfigure request is pending in said queue.

A computer system comprising:

• a host computer;
• a disk array;
• a disk controller for transferring data between a disk array and a host computer, the disk controller comprising:
• a bus;
• a posting memory coupled to said bus;
• reconfiguring processor logic coupled to said bus for reconfiguring the disk array, wherein a source logical volume is reconfigured to a destination logical volume, said source and destination logical volumes being defined on the disk array, and said reconfiguring processor logic including:
• first data transfer logic coupled to said bus for moving data from said source logical volume to said posting memory, said data being moved one transfer unit at a time, second data transfer logic coupled to said bus for moving said source logical volume data from said posting memory to said destination logical volume after one transfer unit of data has been moved to said posting memory;
• host request receiving logic coupled to said bus for receiving a host request from the host computer, said host request asserted for specified blocks of data;
• determining logic coupled to said host request receiving logic for determining if said requested blocks are located in said source logical volume or said destination logical volume;
• and
• indicator logic coupled to said determining logic for pointing said host request to the appropriate one of said source and destination logical volumes,
• wherein the transfer unit of data is a stripe not presently being reconfigured of a data block undergoing reconfiguration.

A computer system comprising:

• a host computer;
• a disk array;
• a disk controller for transferring data between a disk array and a host computer, the disk controller comprising:
• a bus;
• a posting memory coupled to said bus;
• reconfiguring processor logic coupled to said bus for reconfiguring the disk array, wherein a source logical volume is reconfigured to a destination logical volumes, said source and destination logical volumes being defined on the disk array, and said reconfiguring processor logic including:
• first data transfer logic coupled to said bus for moving data from said source logical volume to said posting memory said data being moved one transfer unit at a time;
• second data transfer logic coupled to said bus for moving said source logical volume data from said posting memory to said destination logical volume after one transfer unit of data has been moved to said posting memory;
• host request receiving logic coupled to said bus for receiving a host request from the host computer, said host request asserted for specified blocks of data;
• determining logic coupled to said host request receiving logic for determining if said requested blocks are located in said source logical volume or said destination logical volume;
• and
• indicator logic coupled to said determining logic for pointing said host request to the appropriate one of said source and destination logical volumes,
• wherein said source logical volume has a first stripe size and said destination logical volume has a second stripe size, and wherein said transfer unit has a size equal to the least common denominator of said first and second stripe sizes.

A computer system comprising:

• a host computer;
• a disk array;
• a disk controller for transferring data between a disk array and a host computer, the disk controller comprising:
• a bus;
• a posting memory coupled to said bus;
• reconfiguring processor logic coupled to said bus for reconfiguring the disk array, wherein a source logical volume is reconfigured to a destination logical volume, said source and destination logical volumes being defined on the disk array, and said reconfiguring processor logic including:
• first data transfer logic coupled to said bus for moving data from said source logical volume to said posting memory, said data being moved one transfer unit at a time;
• second data transfer logic coupled to said bus for moving said source logical volume data from said posting memory to said destination logical volume after one transfer unit of data has been moved to said posting memory;
• host request receiving logic coupled to said bus for receiving a host request from the host computer, said host request asserted for specified blocks of data;
• determining logic coupled to said host request receiving logic for determining if said requested blocks are located in said source logical volume or said destination logical volume;
• and
• indicator logic coupled to said determining logic for pointing said host request to the appropriate one of said source and destination logical volumes,
• wherein said reconfiguring processor logic further includes:
• reconfigure request receiving logic coupled to said bus for receiving reconfigure requests from said host computer,
• a queue coupled to said reconfigure request receiving logic, said reconfigure requests being entered into said queue, wherein said reconfiguring processor logic is activated if a reconfigure request is pending in said queue.