Abstract: A method is disclosed for operating a data storage system having one or more network interfaces and a plurality of data storage nodes configured to provide redundant storage locations. The method includes storing a set of node partitions on a given storage node of the plurality of data storage nodes. The method also includes, following a recovery by the given storage node from a malfunction, making a determination for a node partition in the set whether the node partition is current or noncurrent, and processing the node partition according to the determination.

Abstract: A method for ensuring integrity of a data portion written by a controller and stored on a disk drive is provided that includes, among other things, forming at least one queue of a plurality of verification tasks associated with the disk drive and executing at least one verification task associated with the data portion in accordance with the queue. The method also includes identifying each datum of the data portion as one of faulty and not faulty in accordance with the verification task. A data storage apparatus is provided. A device is provided that is adapted to execute a method for ensuring integrity of data written by a controller and stored on a disk drive. A computer-readable storage medium is provided that contains a set of instructions for a computer.

Abstract: I/O requests from hosts in a data storage system are blocked or rate-restricted upon detection of an unbalanced or overload condition in order to prevent timeouts by host computers, and achieve an aggregate reduction of data access latency. The blockages are generally of short duration, and are transparent to hosts, so that host timeouts are unlikely to occur. During the transitory suspensions of new I/O requests, server queues shorten, after which I/O requests are again enabled.

Abstract: A method for reading data from a data storage system, consisting of storing a plurality of copies of the data at a respective plurality of data storage units and receiving at a data port an access request submitted by a host to receive the data. The method further includes transmitting from the port, in response to the access request, a plurality of delivery requests for the data to the respective plurality of data storage units, transmitting from the plurality of data storage units to the port respective responses to the delivery requests, the responses including the data, and accepting at the port an earliest-arriving response consisting of the response to the delivery requests arriving first at the port. The data in the earliest-arriving response is forwarded from the port to the host.

Abstract: A system and method are described to improve the efficiency of copy-on-write operations in a storage system. A partition mapping table is maintained in a cache memory, where the partition mapping table is used to translate logical partitions into physical partitions. A request is received to write one or more blocks BB to a partition PSS, and, upon receiving the request, the pointers in the partition mapping table are interchanged such that data associated with PSS is now associated with a second partition PTT. Next, block(s) BB is written to PSS and an indication is made on the PDSS descriptor that all other data blocks in the partition PSS are invalid.

Abstract: A method for operating a storage system, consisting of performing an allocation of respective partitions of a physical storage resource of the storage system to respective hosts of the storage system. The method also includes changing the allocation while permitting the respective hosts of the storage system to access the physical storage resource.

Abstract: A system and method are described to improve the efficiency of copy-on-write operations in a storage system. A partition mapping table is maintained in a cache memory, where the partition mapping table is used to translate logical partitions into physical partitions. A request is received to write one or more blocks BB to partition PSS, and, upon receiving the request, the pointers in the partition mapping table are interchanged such that data associated with PSS is now associated with PTT. Next, block(s) BB is written to PSS and a read command is issued so that data now associated to PTT is read into the memory and is associated with PSS, except for block(s) BB that was written. In an alternative scenario, the steps of writing block(s) BB to PSS and issuing a read command are performed simultaneously.

Abstract: A system and method are described to improve the efficiency of copy-on-write operations in a storage system. A PDSS descriptor associated with partition PSS and a PDTT descriptor associated with partition PTT are maintained in a cache memory, with partition PSS associated with a source logical unit LUS and partition PTT associated with a source logical unit LUT. An ICP flag is set in the PDSS and PDTT descriptors indicating that the PSS and PTT are undergoing a copy-on-write operation. Data is then dissociated with PTT and locations of each block of the PSS stored in memory are copied from the PDSS descriptor to the PDTT descriptor. A task is then created to fetch blocks of the PSS and the fetched blocks are copied from the PSS to the PTT.

Abstract: A method for creating logical volume snapshots in a data storage system, including receiving a first write command to write first data to a partition of a logical volume, generating a first partition descriptor record (PDR), and storing the first data at a first physical location associated with the first PDR. A snapshot command is then received to form a snapshot of the logical volume, after which a second write command is received to write second data to the partition. In response to the second write command, a second PDR is generated and the second data is stored at a second physical location associated with the second PDR. A pointer between the first PDR and the second PDR is generated. In response to a read command indicating a number of a desired snapshot of the logical volume, the first PDR is accessed using the pointer.

Abstract: A method for maintaining integrity of data in a redundant mass storage system is provided that includes selecting a plurality of scrubbing selections for a memory system in which each of the scrubbing selections selects a data section on the memory system. The method also includes selecting a respective scrubbing implementation for each scrubbing selection in which each of the scrubbing implementations determines a data check. Another exemplary method is provided for ensuring integrity of data stored in a redundant mass storage system. An apparatus is provided for maintaining data integrity in a redundant mass storage system. A computer-readable storage medium containing a set of instructions for a general purpose computer is provided. The set of instructions include a method for ensuring data integrity in a redundant mass storage system.

Abstract: A method for continuous data protection in a storage system, including receiving a first write command to write first data to a partition of a logical volume and then generating a first partition descriptor record (PDR) having a first timestamp. The method further includes storing the first data at a first location, associating the first PDR with the first location, and receiving a second write command, subsequent to the first command, to update the first data with second data. Responsively to the second command, a second PDR having a second timestamp is generated. The second data is stored at a second location, and the second PDR is associated with the second location. The method includes generating a pointer between the first PDR and the second PDR, and accessing the first PDR using the pointer in response to a read command indicating a time prior to the second timestamp.

Abstract: A method for operating a data storage system that includes a plurality of mass storage devices, which are configured to store data redundantly, the method including determining a characteristic service level of one or more of the mass storage devices and defining a reduced service level, which is less than the characteristic service level. The method further includes performing the following steps automatically: detecting the reduced service level on a first mass storage device in the data storage system; determining that data on the first mass storage device is stored redundantly on a second mass storage device in the data storage system; and in response to detecting the reduced service level, diverting an input/output (IO) request for the data directed to the first mass storage device to the second mass storage device, while operating the first mass storage device at the reduced service level.

Abstract: In accordance with further embodiments of the present invention, there is provided a disk controller for managing the delegation of tasks from a disk controller to a disk, including a task delegation module adapted to delegate fetch or destage tasks to the disk in accordance with a relation between an amount of dirty data currently in a cache and a number of pending destage tasks currently being handled by the disk

Abstract: A method for interfacing with a storage system. The storage system has a plurality of elements having a visible relationship with each other, and the storage system is coupled to a system control unit including a display. The method includes: drawing an image of the elements on the display, the image showing the visible relationship, and modifying an appearance of one of the elements in the image to represent a property of the element. The method further includes, in response to a first input from a user of the storage system to the system control unit, drawing an enlarged image of the element and representing the property in the enlarged image. The method also includes, in response to a second input from a user of the storage system to the control unit with respect to the enlarged image, representing a further property of the element in the enlarged image.

Abstract: A method for operating a data storage system that responds to IO data requests from one or more hosts, the system including a first and one or more second mass storage devices, each of the devices having respective data stored therein. The method includes defining an unacceptable level of activity, and performing the following steps automatically, without intervention by a human operator. Detecting the unacceptable level of activity on the first mass storage device; in response to detecting the unacceptable level of activity, transferring the data stored in the first mass storage device to the second mass storage devices, while responding to the IO data requests; reformatting the first mass storage device; and, after reformatting the first mass storage device, transferring the data stored in the second mass storage devices to the first mass storage device, while responding to the IO data requests.

Abstract: A method for copying a logical volume in a data storage system includes forming a first logical volume, storing in physical storage of the data storage system a quantity of data of the first logical volume, and receiving a first command to copy the first logical volume to a second logical volume. In response to the first command, meta-data is formed having a size that is independent of the quantity of the data. In response to a second command to access the data, the meta-data is used to access the data.

Abstract: A method for managing multiple logical volumes in a data storage system, including providing physical storage of a given capacity within the data storage system, and adding a logical volume of a given size within the data storage system so as to cause a total amount of logical storage of the logical volumes in the data storage system to be greater than the given capacity of the physical storage. The method includes verifying, in response to a write command to store data in the logical volume, that a physical storage location is available in the physical storage and, if the physical storage location is available, then storing the data at the physical storage location.

Abstract: A method for copying a logical volume in a data storage system, including forming a first logical volume having one or more logical partitions and storing data at a physical location associated with the one or more logical partitions. The method further includes receiving a first command to copy the first logical volume to a second logical volume, and responsively to the first command, assigning the one or more logical partitions to a meta-volume and linking the meta-volume to the first and second logical volumes. The method also includes receiving a second command to access the data in at least one of the first and second logical volumes, responsively to the second command, using a partition descriptor record associated with the meta-volume to identify the physical location, and providing access to the data at the physical location.

Abstract: Disclosed is a method and system for preparing a mirror batch within a data processing system. Upon determining that a first open batch is approaching or has reached a completion criteria, a controller may cause system elements contributing data to the first open batch to cease acknowledging transaction requests while not ceasing to execute the transaction requests.

Abstract: A method for interfacing with a storage system having a plurality of elements, the elements having a visible relationship with each other, and being coupled to a system control unit including a display. The method includes drawing an image of the elements on the display, the image having the visible relationship and modifying the image of one of the elements to represent a property of the element. The method further includes, in response to an input from a user of the storage system to the system control unit, making a change in the property of the element and representing the change in the image.