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 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 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 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 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, 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: 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 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.

Abstract: According to some embodiments of the present invention, one or more parameters of a received data service request may be compared against a lookup table. Based on one or more priority values stored in the lookup table and associated with the one or more request parameters, the data service request may be assigned a priority level.

Abstract: In accordance with some embodiments of the present invention, there is provided a cache management module for managing a cache memory device, comprising a groups management module adapted to define groups of allocation units in accordance with at least an operative criterion and to create a new group of allocation units whenever it is determined that in accordance with at least the operative criterion none of the one or more existing groups is appropriate to include an allocation unit, and a replacement procedure module adapted to manage the cache in terms of groups of allocation units, rather than in terms of discrete allocation units.

Abstract: Disclosed is a system, method and circuit for mirroring data on a data server. According to some embodiments of the present invention, a primary mirroring module associated with a primary server may be adapted to establish data mirroring connections between the primary server and both a primary slave mirroring module functionally associated with a primary mirror server and with a secondary slave mirroring module functionally associated with a secondary mirror server. When sensing that a mirroring connection with the primary server has been terminated, the primary slave mirroring module may establish a mirroring connection with the second slave mirroring module and may reconcile data between the primary and secondary mirror servers.

Abstract: A system, method and circuit for efficiently managing a cache storage device. A cache storage device may include a cache management module. The cache management module may be adapted to generate a management unit and to associate the management unit with new data that is to be written into the cache. The cache management module may be further adapted to assign two or more allocation units for each management unit, to store the new data in the cache. A cache management module may include a management unit module. The management unit module may be adapted to generate management units associated with predefined global cache management functions. The cache management module may further include an allocation unit module in communication with the management unit module. The allocation unit module may be adapted to assign allocation units for storing data written into the cache.

Abstract: A method for data distribution, including distributing logical addresses among an initial set of devices so as provide balanced access, and transferring the data to the devices in accordance with the logical addresses. If a device is added to the initial set, forming an extended set, the logical addresses are redistributed among the extended set so as to cause some logical addresses to be transferred from the devices in the initial set to the additional device. There is substantially no transfer of the logical addresses among the initial set. If a surplus device is removed from the initial set, forming a depleted set, the logical addresses of the surplus device are redistributed among the depleted set. There is substantially no transfer of the logical addresses among the depleted set. In both cases the balanced access is maintained.

Abstract: A method for data distribution, including distributing logical addresses among an initial set of devices so as provide balanced access, and transferring the data to the devices in accordance with the logical addresses. If a device is added to the initial set, forming an extended set, the logical addresses are redistributed among the extended set so as to cause some logical addresses to be transferred from the devices in the initial set to the additional device. There is substantially no transfer of the logical addresses among the initial set. If a surplus device is removed from the initial set, forming a depleted set, the logical addresses of the surplus device are redistributed among the depleted set. There is substantially no transfer of the logical addresses among the depleted set. In both cases the balanced access is maintained.

Abstract: A method for data distribution, including distributing logical addresses among an initial set of devices so as provide balanced access, and transferring the data to the devices in accordance with the logical addresses. If a device is added to the initial set, forming an extended set, the logical addresses are redistributed among the extended set so as to cause some logical addresses to be transferred from the devices in the initial set to the additional device. There is substantially no transfer of the logical addresses among the initial set. If a surplus device is removed from the initial set, forming a depleted set, the logical addresses of the surplus device are redistributed among the depleted set. There is substantially no transfer of the logical addresses among the depleted set. In both cases the balanced access is maintained.

Abstract: Some embodiments of the present invention relate to a method and a circuit for managing the prefetching of data into a cache. According to some embodiments of the present invention a prefects controller may be adapted to trigger a prefetch operation for prefetching one or more data segments into the cache together with at least one segment to be fetched, and may be further adapted to establish a number of data segments to be prefetched together with the at least one segment to be fetched. According to some embodiments of the present invention, the prefetch controller may be adapted to establish what number of segments are to be prefetched at least in accordance with the number of successive segments, including one, already in the cache, which are spaced apart by no more than a predetermined number of segments relative to the at least one segment to be fetched.