Abstract: A snapshot tree structure includes a base volume storing a current user data, a first snapshot descending from the base volume, and a second snapshot descending from the first snapshot, wherein the second snapshot was created prior to the first snapshot. The first snapshot includes a first table corresponding to first portions of block addresses, a second table corresponding to second portions of the block addresses, and a third table to third portions of the block addresses. The first table includes an entry with a pointer to the second table. The second table includes an entry with a pointer to the third table. The third table includes an entry with a pointer to a data of the base volume before the data is modified in the base volume.

Abstract: A chain of snapshots includes read-write snapshots descending from a read only snapshot. The read only snapshots presents a constant view of the data at the time the read only snapshot is created, and the read-write snapshot starts with the view but can be modified by the user without changing the view of its parent snapshot (e.g., the read only snapshot). Accordingly, the read-write snapshot can be written for various testing purposes while the read only snapshot remains undisturbed to preserve the original data.

Abstract: A disk enclosure includes a first enclosure controller powered by a first voltage circuit and coupled to a first I2C bus, a second enclosure controller powered by a second voltage circuit and coupled to a second I2C bus, and a switch coupled between the first and the second I2C buses. The first switch de-couples the first and the second I2C buses when the voltage output of the second voltage circuit falls below a predetermined threshold.

Abstract: A method for resynchronizing a primary volume in a primary system and a secondary volume in a secondary system over a network includes, when a network connection between the primary system and the secondary system is interrupted, creating a snapshot of the primary volume and determining data updates transmitted from the primary system to the secondary system that were not acknowledged by the secondary system. The method further comprises, when the network connection is reestablished, determining differences between the snapshot and the primary volume, transmitting the differences and the unacknowledged data updates from the primary system to the secondary system, and updating the secondary volume with the differences and the unacknowledged data, wherein the secondary volume becomes an updated copy of the primary volume.

Abstract: A data storage system and method capable of reducing the operating temperature of the data storage system, removing any overheating storage devices from operation, reconstructing data, and evacuating data from the overheating storage devices before the devices and the data are damaged or lost.

Abstract: A data storage system includes a plurality of disk drives for data storage. A storage server controls the reading and writing of data to the disk drives. The storage server can be tested prior to connecting the disk drives and other components of the data storage system by connecting ports of the storage server to other ports of the storage server. One of the connected ports is changed from an initiator to a target to simulate a the target state of a disk drive. The server can test itself at normal data transfer rates using the initiator-target pair just as if it was testing a normal server/disk drive connection, but without having to test the actual disk drive and without having to detect or distinguish any problems that may exist with the disk drive and its connection, or other components that may be in the loop.

Abstract: A system and method for detecting and handling spurious input are disclosed. In one embodiment, upon receipt of an interrupt signal, a device activates command and keystroke timeouts. The keystroke timeout may have a shorter duration than the command timeout and may be reset upon receipt of a keystroke. At the first expiration of either the keystroke or command timeouts, the device generates a user message. At the second expiration of either the keystroke or command timeouts, the device resumes initialization or resets.

Abstract: A method is provided for synchronization of a backup copy of a volume of memory represented by a snapshot tree. The snapshot tree includes a plurality of snapshot volumes, each snapshot volume corresponding to a respective snapshot of the volume of memory. The method comprises the following: determining whether there are any exceptions in any of the snapshot volumes in the snapshot tree between and including the snapshot volumes corresponding to a first and a second snapshot; if there are exceptions, processing for the exceptions to synchronize the backup copy of the memory volume; otherwise, if there are no exceptions, ignoring the snapshot volumes.

Abstract: A system and method are provided for permitting a console to be connected to an external port of a first node for monitoring and controlling the first node in a default mode. The first node may also operate in a terminal mode in which an internal port of the first node is connected to an internal port of a second node to permit the console and the second node to communicate via the first node.

Abstract: A method for notifying events to a node in a cluster includes (1) receiving a first event message and a second event message, (2) queuing the first and the second event messages, (3) sending the first event message to a first service callback, wherein the first service callback calls a first callback function to handle the first event message, (4) sending the first event message to a second service callback after (a) a the first service callback has handled the first event message and (b) a corresponding first service callback at a member node has handled the first event message, wherein the second service callback calls a second callback function to handle the first event message, and (5) sending the second event message to the first service callback after the first and the second callback functions have handled the first event message, wherein the first service callback calls the first callback function to handle the second event message.

Abstract: A disk enclosure includes a first plurality of I2C elements powered by a first power domain and a second plurality of I2C devices powered by a second power domain. The first plurality of I2C elements are coupled via a first I2C bus and the second plurality of I2C elements are coupled via a second I2C bus. An enclosure controller has a third I2C bus selectively coupled via a multiplexer to the first or the second I2C bus.

Abstract: In one embodiment of the invention, a virtual volume is divided into “filled” and “empty” virtual volume (VV) regions. Empty VV regions are mapped to a special zero logical disk that does not consist of any physical disk regions. When a host writes to an empty VV region, a logical disk (LD) region is allocated to the empty VV region so the formerly empty VV region becomes a filled VV region mapped to the allocated LD region. If there are no LD regions available, a new logical disk is created. Additional physical storage can be added to the storage server to create new logical disks as the use of the virtual volume grows. Physical allocation warning points and limits allow the system administrator to be alerted to and to control physical allocation for each individual VV and the set of VVs drawing from the same data allocation control structure (DC).

Abstract: A method is provided for communicating data in an interconnect system comprising a plurality of nodes. In one aspect, the method includes: issuing a command packet from a first node, the command packet comprising a respective header quadword and at least one respective data quadword for conveying a command to a second node, wherein the command is selected from a group comprising a direct memory access (DMA) command, an administrative write command, a memory copy write command, and a built in self test (BIST) command; receiving the command packet at the second node; issuing an acknowledgement packet from the second node, the acknowledgement packet comprising a respective header quadword for conveying an acknowledgement that the command packet has been received at the second node.

Abstract: A method for new nodes to join a cluster in a serial sequence includes (a) a new node transmitting a first type of request to join the cluster and (b) the new node determining if it has to back off the first type of request. The new node has to back off if (1) it has received a second type of request to join the cluster from another new node, (2) it has received the first type of request with a higher sequence number from another new node, (3) it has received the first type of request with a lower node number from another new node, or (4) a member node of the cluster is in a busy state. The new node transmits the first type of request, receives the first type of request, and receives the second type of request through primary links to the new nodes and member nodes of the cluster.

Abstract: An enclosure is disclosed for housing multiple electronic devices. In one embodiment, the enclosure includes a chassis having a floor and opposing sidewalls. Discrete first and second midplanes, each having an opening formed therein, may be disposed in an interior portion of the chassis on opposite sides of a divider wall. The first and second midplanes may be configured to mate to at least one air displacement unit on a back surface of the associated midplane and to mate to at least one device sled on a front surface of the associated midplane. An opening is formed in each midplane adjacent the associated air displacement unit to permit air to pass through the opening.

Abstract: A disk enclosure includes a first group of one or more power sources that powers a first group of elements in a first power domain and a second group of power sources that powers a second group of elements in a second domain. The disk enclosure also includes a first voltage circuit and a second voltage circuit that are each powered by the first group of power sources and the second group of power sources. The first voltage circuit powers a third group of elements while the second voltage circuit powers a fourth group of elements.

Abstract: A method is provided to allow a system administrator of a utility storage server to provision virtual volumes several times larger than the amount of physical storage within the storage server. A virtual volume is a virtual representation of multiple disks as a single large volume to a host or an application. In one embodiment, a virtual volume comprises an exception list containing the set of differences from dummy base volume consisting of all zeros. This exception list can be made up of address tables that map virtual volume pages to logical disk pages. As storage demand grows, additional storage is allocated for the address tables and the data pages from separate pools of storage. If any of the pools runs low, more logical disk regions are allocated to that pool.

Abstract: A new method to control differential signal trace impedance allows flexible use of different signal trace width and spacing while maintaining constant differential impedance in printed circuit boards. Differential impedance of a signal pair is determined by the geometry of individual traces and the spacing between traces. The value of the differential impedance is inversely proportional to signal trace width and directly proportional to signal trace spacing. By decreasing or increasing trace width and spacing simultaneously, a constant differential impedance can be achieved.

Abstract: An electronic device mount assembly is disclosed for permitting an electronic device to be mounted within an enclosure. In one embodiment, the electronic device mount assembly includes a pair of braces operable to be secured to opposing sides of an electronic device mount assembly. Each of the braces having at least one fastener mounted thereon. A base member is also disclosed that includes raised connection assemblies operable to receive the fasteners of the first pair of braces, for securing the electronic device to the base member.

Abstract: A data storage system includes a plurality of nodes for providing access to a data storage facility. Each node has a computer-memory complex to provide general purpose computing for the node, a node controller to control data transfers through the respective node, and a cluster memory to buffer data for the data transfers. A plurality of communication paths interconnect the nodes, with a separate communication path provided for each two nodes of the data storage system.