Abstract: A method for a storage controller to rebalance storage components within a storage tier is provided. The method maintains a linked list for each component, and each component includes a plurality of pages. Each linked list is ordered according to hot and cold pages and includes an identifier for each page. The method calculates a percent range of hot and cold pages for each component, and identifies a fullest and least full component. The method compares a random percent to the hot and cold percent ranges for the fullest component. If the random percent falls within the hot range, the method moves a selected hot page from the fullest component to an empty page in the least full component. If the random percent falls within the cold range, the method moves a selected cold page from the fullest component to an empty page in the least full component.

Abstract: A system, device, and method are provided for managing one or more computer resource systems. More specifically, the present invention provides for the automated maintenance of a computer resource and gradual change of management policies based upon a state of the computer resource. Moreover, the present invention is capable of generating commands related to changing the configuration of the computer resource and maintaining a log of generated commands for later reference by a system administrator. Further, the present invention includes one or more human user written policies, in some computer understandable format, to manage the system and accomplish specific goals based on the system's dynamic nature or behavior.

Abstract: A method for maximizing I/O requests to a target port is provided. The method includes a storage controller obtaining an initiator allowed queue depth, receiving an I/O request and a current sequence identifier from an initiator logged into the target port, and determining if the initiator allowed queue depth is equal to a first queue depth corresponding to the initiator. If the initiator allowed queue depth is equal to the first queue depth then returning a queue full indication and a maximum sequence identifier equal to the current sequence identifier to the initiator. If the initiator allowed queue depth is not equal to the first queue depth then placing the I/O request on a queue, incrementing the first queue depth, and adjusting the maximum sequence identifier. Adjusting the maximum sequence identifier includes adding the current sequence identifier to the initiator allowed queue depth and subtracting the first queue depth.

Abstract: A method, device, and system for resetting snapshots are provided. The reset of a snapshot incorporates the traditional snapshot delete and snapshot create operations into a single operation. Additionally, a snapshot created under the reset operation may receive an array partition from a snapshot being deleted under the same snapshot reset operation thereby retaining its identifying characteristics.

Abstract: A method, device, and system for resetting snapshots are provided. The reset of a snapshot incorporates the traditional snapshot delete and snapshot create operations into a single operation. Additionally, a snapshot created under the reset operation may receive an array partition from a snapshot being deleted under the same snapshot reset operation thereby retaining its identifying characteristics.

Abstract: A network storage appliance is disclosed. The appliance includes a chassis enclosing a backplane, and a server enclosed in the chassis and coupled to the backplane. The appliance also includes storage controllers enclosed in the chassis, each coupled to the backplane, which control transfer of data between the server and storage devices coupled to the storage controllers. The storage controllers also control transfer of data between the storage devices and computers networked to the appliance and external to the appliance. The storage controllers and the server comprise a plurality of hot-replaceable blades. Any one of the plurality of blades may be replaced during operation of the appliance without loss of access to the storage devices by the computers. In one embodiment, the server executes storage application software, such as backup software for backing up data on the storage devices, such as to a tape device networked to the server.

Abstract: A data storage system with a controller that receives shock data from a shock detection sensor and methods utilizing such a controller are provided. The data storage system controller receives information or signals regarding shock events from a shock sensor, enabling the data storage system controller to take remedial action. The particular remedial action taken may be dependent on the severity of the detected shock event. The data storage system controller may receive information regarding shock events from shock sensors provided separately from the data storage system controller, allowing the data storage system controller to take remedial action that is tailored to the locale of a shock event.

Abstract: A data storage system controller having a shock detection sensor and methods utilizing such a controller are provided. The data storage system controller receives information or signals regarding shock events from the associated shock sensor, enabling the data storage system controller to take remedial action. The particular remedial action taken may be dependent on the severity of the detected shock event. The data storage system controller may also receive information regarding shock events from shock sensors provided separately from the data storage system controller, allowing the data storage system controller to take remedial action that is tailored to the locale of a shock event.

Abstract: A storage system includes two RAID controllers, each having two SAS initiators coupled to a zoning SAS expander. The expanders are linked by an inter-controller link and create a SAS ZPSDS. The expanders have PHY-to-zone mappings and zone permissions to create two distinct SAS domains such that one initiator of each RAID controller is in one domain and the other initiator is in the other domain. The disk drives are dual-ported, and each port of each drive is in a different domain. Each initiator can access every drive in the system, half directly through the local expander and half indirectly through the other RAID controller's expander via the inter-controller link. Thus, a RAID controller can continue to access a drive via the remote path in the remote domain if the drive becomes inaccessible via the local path in the local domain.

Abstract: A method, device, and system are provided for determining when to re-initialize a backing store in a data storage system. More specifically, when all snapshots associated with a specified backing store are either being deleted or are marked for deletion the backing store is re-initialized rather than deleting each snapshot independently. The re-initialization of the backing store provides for a quicker way to delete all snapshots than can be achieved by deleting each snapshot independently.

Abstract: A method and device for managing snapshot data is provided. Snapshots may be created having a preserved data area and a write data area. The preserved data area is used to maintain snapshot data corresponding to the point-in-time when the snapshot was created while the write data area is used to facilitate host read/write access to the snapshot. By maintaining two separate areas, the snapshot can be written to without altering the point-in-time representation of the snapshot.

Abstract: A method and apparatus for obscuring data held on a storage device associated with a storage system controller are provided. Data is obscured by swapping bit values according to a scrambling key, before the unit of data is stored on the storage device. Furthermore, multiple swaps or translations of bit values can be performed in sequence on a single unit of data. In order to descramble a unit of data, the translations of bit values applied during scrambling are performed in reverse order. Alternatively or in addition, data can be obscured by scrambling the bit values of an address associated with a unit of data.

Abstract: A storage controller that operates under elevated temperature conditions includes a memory, a memory controller, and a CPU that detects a temperature of the memory controller has exceeded a threshold while operating at a first frequency and responsively places the memory into self-refresh mode, reduces the memory controller frequency to a second frequency, and then takes the memory out of self-refresh mode. The clock frequency of a bus bridge or communications link circuit may also be reduced when their temperatures exceed a threshold. The bus bridge may deny access to requestors of access to the memory while the frequency is being reduced. Message transfers on a communications link between redundant storage controllers in a system may be suspended while the link frequency is being reduced. Finally, the system may fail over to one controller while the other controller reduces the frequencies and then fail back.

Abstract: A method, device, and system are provided for rollback of a master volume in a data storage system. More specifically, when a rollback is requested, snapshots that are involved in the rollback can be deleted during the rollback. This is accomplished by deleting the snapshot partition but not the actual snapshot data. Rather, the snapshot data is retained until the rollback is complete incase some of the snapshot data needs to be written to the master volume as part of the rollback.

Abstract: Methods and systems for managing user access to a storage system controller are provided. In particular, user login requirements and permissions are administered, and individual user and external user interface pairs are tracked, through a user table and a session table established as part of the storage system controller. The external user interfaces may be interconnected to the storage system controller through different networks and/or protocols. User authentication and access levels are established with reference to a user table, while sessions for different user and external interface pairs are maintained in the session table.

Abstract: A write-caching RAID controller includes a CPU that manages transfers of posted-write data from host computers to a volatile memory and transfers of the posted-write data from the volatile memory to a redundant array of storage devices when a main power source is supplying power to the RAID controller. A memory controller transfers the posted-write data received from the host computers to the volatile memory and transfers the posted-write data from the volatile memory for transfer to the redundant array of storage devices as managed by the CPU. The memory controller flushes the posted-write data from the volatile memory to the non-volatile memory when main power fails, during which time capacitors provide power to the memory controller, volatile memory, and non-volatile memory, but not to the CPU, in order to reduce the energy storage requirements of the capacitors.

Abstract: The verification of fault-tolerant connections between redundant controller pairs and nodes is provided. In particular, a node identifier seen at one port of the controllers is compared to the node identifier seen at another port of the controllers. In response to determining that proper connections have not been made, an error or warning signal may be generated. In addition, where supported by dynamic port configuration, the ports of the controllers may be reconfigured in response to the comparison to effect proper connections. In response to determining that proper connections have been made, a signal verifying that proper connections have been made may be generated.

Abstract: A RAID controller uses a method to identify a storage device of a redundant array of storage devices that is returning corrupt data to the RAID controller. The method includes reading data from a location of each storage device in the redundant array a first time, and detecting that at least one storage device returned corrupt data. In response to detecting corrupt data, steps are performed for each storage device in the redundant array. The steps include reading data from the location of the storage device a second time without writing to the location in between the first and second reads, comparing the data read the first and second times, and identifying the storage device as a failing storage device if the compared data has a miscompare. Finally, the method includes updating the location of each storage device to a new location and repeating the steps for the new location.

Abstract: A method, device, and system are provided for re-initializing a backing store in a data storage system. More specifically, when all snapshots associated with a specified backing store are either being deleted or are marked for deletion the backing store is re-initialized rather than deleting each snapshot independently. The re-initialization of the backing store provides for a quicker way to delete all snapshots than could previously be achieved when each snapshot was deleted independently.

Abstract: A method and device for performing a volume copy is provided. The volume copy method allows access to both the Volume Copy Source and Volume Copy Target while the volume copy process is occurring. This allows a system administrator to initiate a volume copy without worrying that host access to the Volume Copy Source and Volume Copy Target will be interrupted.