Abstract: A method and system manages a virtual tape library history database. The method includes triggering an update of the virtual tape library history database in response to detecting a change related to a tape in a virtual tape library state table, where the update is asynchronous from processing of small computer system interface (SCSI) or command line interface (CLI) commands handled by a virtual tape library, and adding a record to a virtual tape history table in the virtual tape library history database, the virtual tape history table corresponding to the tape, where the record includes information about the change, where the virtual tape history table functions as a log of activity for the tape.

Abstract: A network-attached system, device, and method supports storage devices having a plurality of storage device types, such as Fibre Channel storage devices, ATA storage devices, serial attached SCSI storage devices, serial ATA storage devices, and solid stage storage devices. Each storage device having a different storage device type is associated with a set of management rules. The management rules may includes rules for such things as identifying the dedicated storage device, configuring the dedicated storage device, sending disk protocol messages to the dedicated storage device, handling disk protocol message received from the dedicated storage device, and handling error and exception conditions.

Abstract: A system and method described herein allows a virtual tape library (VTL) to perform multiple simultaneous or parallel read/write or access sessions with disk drives or other storage media, particularly when subject to a sequential SCSI-compliant layer or traditional limitations of VTLs. In one embodiment, a virtualizing or transaction layer can establish multiple sessions with one or more clients to concurrently satisfy the read/write requests of those clients for physical storage resources. A table or other data structure tracks or maps the sessions associated with each client and the location of data on the physical storage devices.

Abstract: A system and method described herein allows a virtual tape library (VTL) to perform multiple simultaneous or parallel read/write or access sessions with disk drives or other storage media, particularly when subject to a sequential SCSI-compliant layer or traditional limitations of VTLs. In one embodiment, a virtualizing or transaction layer can establish multiple sessions with one or more clients to concurrently satisfy the read/write requests of those clients for physical storage resources. A table or other data structure tracks or maps the sessions associated with each client and the location of data on the physical storage devices.

Abstract: A method for managing storage space in a storage port queue includes establishing a watermark for the storage port queue. The method further receives, at the storage port associated with the storage port queue, a command having an initiator-target-LUN (ITL) nexus associated therewith. Upon receiving the command, the method determines whether the used space in the storage port queue has reached the watermark. In the event the used space has not reached the watermark, the method processes the command. In the event the used space has reached the watermark and a specified number of commands for the ITL nexus are already present in the storage port queue, the method rejects the command. Otherwise, the method may process the command.

Abstract: An example method for memory resource provisioning using SAS zoning can include a serial attached Small Computer System Interface (SCSI) (SAS) switch and a provisioning manager (PM) executing on the SAS switch. A plurality of servers are communicatively coupled to the SAS switch, each server executing an operating system (OS) having access to one or more OS volumes. A host provisioning agent (HPA) executes on the OS of each of the plurality of servers. A plurality of memory resources are communicatively coupled to the SAS switch. Each memory resource can have a number of physical hard drives. A first portion of the memory resources is associated with zone groups corresponding to the plurality of servers. A second portion of the memory resources is associated with a provisioning zone group (PZG) hidden from the plurality of servers but available to the PM.

Abstract: A network-attached system, device, and method supports storage devices having a plurality of storage device types, such as Fibre Channel storage devices, ATA storage devices, serial attached SCSI storage devices, serial ATA storage devices, and solid stage storage devices. Each storage device having a different storage device type is associated with a set of management rules. The management rules may includes rules for such things as identifying the dedicated storage device, configuring the dedicated storage device, sending disk protocol messages to the dedicated storage device, handling disk protocol message received from the dedicated storage device, and handling error and exception conditions.

Abstract: A method for managing storage space in a storage port queue includes establishing a watermark for the storage port queue. The method further receives, at the storage port associated with the storage port queue, a command having an initiator-target-LUN (ITL) nexus associated therewith. Upon receiving the command, the method determines whether the used space in the storage port queue has reached the watermark. In the event the used space has not reached the watermark, the method processes the command. In the event the used space has reached the watermark and a specified number of commands for the ITL nexus are already present in the storage port queue, the method rejects the command. Otherwise, the method may process the command. A corresponding apparatus and computer program product are also disclosed herein.

Abstract: Storage virtualization systems and methods that allow customers to manage storage as a utility rather than as islands of storage which are independent of each other. A demand mapped virtual disk image of up to an arbitrarily large size is presented to a host system. The virtualization system allocates physical storage from a storage pool dynamically in response to host IO requests, e.g., SCSI I/O requests, allowing for the amortization of storage resources-through a disk subsystem while maintaining coherency amongst I/O RAID traffic. In one embodiment, the virtualization functionality is implemented in a controller device, such as a controller card residing in a switch device or other network device, coupled to a storage system on a storage area network (SAN). The resulting virtual disk image that is observed by the host computer is larger than the amount of physical storage actually consumed.

Abstract: A process, apparatus, and system stores data check information on an electronic storage medium that uses standard sector data field sizes. The check information may include a cyclic redundancy check (CRC), a logical block address (LBA), a longitudinal redundancy check (LRC), state information, a sequence number, or other information to identify data state, misplacement, or corruption. The check information, instead of being appended to the data within the data sector, may be stored in an independent check sector. The check information corresponding to multiple data sectors may also be aggregated and stored in a single check sector. The process or apparatus may be incorporated in a storage system controller, a RAID controller, a software SCSI stack in a computer, an operating system, a storage device driver, or another appropriate application that interfaces with standard and commodity storage system components.

Abstract: One embodiment of the present invention sets forth a technique for emulating a floppy disk drive using network storage services. An application executing on a diskless computing device generates INT 13 access requests to gain access to a floppy disk image residing on a storage server. The INT 13 access requests are directed to a translation function that maps cylinder head sector (CHS) addresses and commands native to floppy disk media to linear block addresses (LBA) and commands used to access data within SCSI devices. An iSCSI initiator residing within the diskless computing device directs the LBA requests to an iSCSI target residing within the storage server to access a LUN residing on the storage server that contains a floppy disk image. The application is then able to conduct access requests to the floppy disk image as though a physical floppy disk drive were present on the diskless computing device.

Abstract: A process, apparatus, and system stores data check information on an electronic storage medium that uses standard sector data field sizes. The check information may include a cyclic redundancy check (CRC), a logical block address (LBA), a longitudinal redundancy check (LRC), state information, a sequence number, or other information to identify data state, misplacement, or corruption. The check information, instead of being appended to the data within the data sector, may be stored in an independent check sector. The check information corresponding to multiple data sectors may also be aggregated and stored in a single check sector. The process or apparatus may be incorporated in a storage system controller, a RAID controller, a software SCSI stack in a computer, an operating system, a storage device driver, or another appropriate application that interfaces with standard and commodity storage system components.

Abstract: A data storage system and method of scheduling commands in such a data storage system are provided in which commands are stored in a command sort queue and a scheduled command queue. Commands in the command sort queue are sorted and assigned a priority. Eventually, commands in the command sort queue are transferred to the scheduled command queue. Commands in the scheduled command queue are executed without further sorting. The desired queue depth or size of the scheduled command queue is determined as a function of both the queue depth of the command sort queue and a command execution rate value which is indicative of the rate at which commands in the scheduled command queue are executed. The desired queue depth may be dynamically determined using the queue depth of the command sort queue and the command execution rate value as inputs to a look-up table. The data storage system may include a small computer system interface (SCSI) disc (or “disk”) drive which executes commands from a host system.

Abstract: SAS/SATA Store-Forward (SSSF) buffering enables SAS/SATA block storage devices capable of slower physical link rates to transfer data at a SAS topology data rate. 6 Gbps SAS and SATA disk drives can exchange data at 12 Gbps with 12 Gbps hosts through 12 Gbps SAS expanders employing an SSSF device. The SSSF device improves data transfer performance in the storage area network by optimizing host-side link utilization. The device includes a host-side interface communicating with the host at a host-side rate, a drive-side interface communicating with the target at a drive-side rate equal to or less than the host-side rate, a buffer receiving SAS frames or SATA FIS's, and control logic to control communication between the host-side interface and buffer at the host-side rate and between the drive-side interface and the buffer at the drive-side rate.

Abstract: A technique enables efficient access to logical unit numbers (luns) or virtual disks (vdisks) stored on a storage system, such as a multi-protocol storage appliance. The technique allows a grouping of initiators by a “human friendly” logical name that is mapped to a lun or vdisk on the storage appliance. The initiators are clients operating in, e.g., a storage area network (SAN) environment that initiate requests for the vdisk using block-based access protocols, such as the Small Computer Systems Interface (SCSI) protocol encapsulated over TCP/IP (iSCSI) or over fibre channel (FCP). The technique enables access to the vdisk by all initiators that are members of the initiator group (igroup). An igroup is a logical named entity that is assigned to one or more addresses associated with one or more initiators. These addresses may comprise fibre channel (FC) world wide name (WWN) or iSCSI name identifiers (IDs).

Abstract: A method for selecting a next command to execute from a set of SCSI commands where the commands are gracefully aged and performance of a disk drive is improved. An execution threshold age, a pool threshold age, and an age threshold age are used to determine what command is executed next. A mechanical time delay is calculated for a command based on the time required to position the read/write head over the data location requested in each command. A command age is calculated based on a current time and the time the command was received from the host. The command age is checked against the execution threshold age and pool threshold age. Any commands that have aged beyond the execution threshold age are executed. If the oldest command has aged beyond the age threshold age, then any command that has both aged beyond the pool threshold age and has the smallest mechanical time delay is executed, otherwise the command with the smallest mechanical time delay is executed.

Abstract: A method and apparatus for writing data to a storage device such as a hard disk drive in which two write commands from an initiator are processed as a single command at the storage device. A first request is received from a small computer systems interface (SCSI) bus to write a first set of data to a storage device. The first set of data is transferred to memory for temporary storage prior to transfer to the storage device. Thereafter, a second write request is received to write a second set of data to the storage device in which the write request includes a logical block address. An ending logical block address determined after transferring the first set of data is compared to the logical block address of the second request to determine whether the second set of data can be written to the storage device along with the first set of data as a single write operation based on the comparison of the logical block address of the second request and the ending logical block address.

Abstract: An integrated circuit implementing a storage-shelf router, used in combination with path controller cards and optionally with other storage-shelf routers, to interconnect SATA disks within a storage shelf or disk array to a high-bandwidth communications medium, such as an FC arbitrated loop. Various embodiments of the present invention provide a tunneling mechanism through the storage-shelf interface provided by one or more storage-shelf routers within a storage shelf to enable external processing entities to directly access various components within the storage shelf. In one embodiment of the present invention, a WRITE-BUFFER command and a READ-BUFFER command are added to the command interface supported by storage-shelf router. These commands are exchanged via the FCP protocol over the fiber channel in the same manner that SCSI commands are packaged within the FCP protocol.