Abstract: Methods and apparatus are disclosed for maintaining and using entries in one or more associative memories. A last bit of a prefix is checked, and based on this result, the entry is placed into one of two classes of associative memory entries. The entry can then be identified within the associative memory by performing a lookup operation using the prefix padded with ones if the last bit of the prefix is zero or with zeros if the last bit is one to fill out the remaining bits of the lookup word. Entries of different classes of entries are typically either stored in different associative memories, or in the same associative memory with each of these entries including a class specific identifier. Among other applications, these entries can be used to locate a prefix and to store a tree data structure in the one or more associative memories.

Abstract: Disclosed is a data recovery mechanism associated with a data writing process in a storage area network (SAN). In general, a data writing mechanism is provided so that a particular host can write data to a storage device in a particular SAN session. One specific example of a data writing mechanism is a data tapping mechanism that provides a copy of this data to an appliance. The data recovery mechanism allows the appliance to recover data from the particular target, for example, when the data was unsuccessfully mirrored to the appliance during the data tapping or when the appliance needs to obtain the data that was written prior to a data tapping procedure being initiated. In one embodiment, the data recovery mechanism is set up so that the appliance can recover data from the target by mimicking the particular host.

Abstract: Disclosed is a a session modification mechanism for altering a data tapping process in a storage area network (SAN). In general, a data tapping mechanism is set up so that an appliance receives SAN data that is tapped from a particular SAN session. That is, the data tapping mechanism provides to a particular appliance a copy of the SAN data that is being written from a particular host to a particular storage device. The session modification mechanism allows the appliance to alter various aspects of the SAN session that is to be (or is being) tapped.

Abstract: Disclosed are methods and apparatus for detecting anomalies in a storage area network (SAN). Provided are one or more anomaly type(s) and corresponding actions to be performed when the one or more anomaly types are detected. Traffic in the SAN is then inspected in order to detect the one or more provided anomaly type(s). When a one of the provided one or more anomaly type(s) is detected, one or more of the corresponding action(s) is performed. The provided anomaly type(s) may include one or more of the following: a read or write access pattern anomaly, excessive login or control requests, a bandwidth usage anomaly, a configuration anomaly, and a hardware anomaly.

Abstract: A technique is provided for implementing online mirroring of a volume in a storage area network. A first instance of the volume is instantiated at a first port of the fibre channel fabric for enabling I/O operations to be performed at the volume. One or more mirroring procedures may be performed at the volume. In at least one implementation, the first port is able to perform first I/O operations at the volume concurrently while the mirroring procedures are being performed at the first volume. In one implementation, the mirroring procedures may be implemented at a fabric switch of the storage area network. Additionally, in at least one implementation, multiple hosts may be provided with concurrent access to the volume during the mirroring operations without serializing the access to the volume.

Abstract: A technique is provided for implementing online mirroring of a volume in a storage area network. A first instance of the volume is instantiated at a first port of the fibre channel fabric for enabling I/O operations to be performed at the volume. One or more mirroring procedures may be performed at the volume. In at least one implementation, the first port is able to perform first I/O operations at the volume concurrently while the mirroring procedures are being performed at the first volume. In one implementation, the mirroring procedures may be implemented at a fabric switch of the storage area network. Additionally, in at least one implementation, multiple hosts may be provided with concurrent access to the volume during the mirroring operations without serializing the access to the volume.

Abstract: A technique is provided for facilitating information management in a storage area network. The storage area network may utilize a fibre channel fabric which includes a plurality of ports. The storage area network may also comprise a first volume which includes a first mirror copy and a second mirror copy. The storage area network may further comprise a mirror consistency data structure adapted to store mirror consistency information. A mirror consistency check procedure is performed to determine whether data of the first mirror copy is consistent with data of the second mirror copy. According to one implementation, the mirror consistency check procedure may be implemented using the consistency information stored at the mirror consistency data structure.

Abstract: Disclosed is apparatus and methods for enabling an appliance to receive data being sent between any host of a host cluster to a specified storage device's logical unit (LUN) in a single stream or session. In one embodiment, a data virtual target is initially set up for a specified storage device LUN so that data written from a host to the specified storage device LUN is received by the DVT. An appliance then sends a session request to mirror data that is sent to the DVT (and specified storage device LUN) to a specified LUN of the appliance. The session request is not host specific. That is, data that is sent by any host to the DVT is mirrored to the same appliance LUN.

Abstract: Disclosed are methods and apparatus for data tapping within a storage area network (SAN) and providing tapped data to a third party device, such as an appliance. In general, mechanisms are provided in a SAN to allow a data tap of data flowing between an initiator and a target. In one implementation, a data virtual target (DVT) in created in a network device to intercept data sent by a specific initiator to a specific logical unit of a specific target. The data or a copy of the data is sent to both the specific logical unit of the specific target and to an appliance. The data routing may be accomplished by use of a virtual initiator (VI), which is configured to send the data (or a copy of the data) to the specific target and the appliance. In a transparent mode of operations, the DVT has a same PWWN (port world wide name) and FCID (fibre channel identifier) as the specific target. In a first proxy mode of operation, the DVT has a different PWWN and FCID than the specific target.

Abstract: A technique is provided for implementing online restriping of a volume in a storage area network. A first instance of the volume is instantiated at a first port of the fibre channel fabric for enabling I/O operations to be performed at the volume. While restriping operations are being performed at the volume, the first port is able to concurrently perform I/O operations at the volume.

Abstract: Methods and apparatus provide formation and management of intelligent application clusters in a storage area network. Disk arbitration mechanisms ensure that a cluster is owned by a single member. In the event of a network partition, each cluster member involved arbitrates to gain ownership of a cluster. High availability mechanisms allow monitoring of system resources and effective failover capabilities.

Abstract: A scalable NAS file system and protocols for implementing CIFS thereon are disclosed. In certain embodiments, the protocols implement the CIFS protocol on a scalable file server architecture having one or more protocol termination nodes, one or more file server nodes, and one or more disk controller nodes. Among the features that may be specifically implemented are tree access, file access, user authentication, locking, state maintenance, and failover of protocol termination nodes and file server nodes.

Abstract: An apparatus and method of using same for associating a tag with each packet in an ATM switch to eliminate the need for an OVC table, thus saving both egress processing time and memory resources. The tag includes both a type of switching identifier and a per-logical-interface or per-external-VC information field. A packet received by the egress packet processing engine has associated with it (by the control plane) a frame control word containing a new cell header (NCH) corresponding to the OVC on which the packet was received from the fabric. This NCH contains the tag used to expedite egress processing. In one embodiment of the present invention, The tag value is provided in two fields, a tag type and a tag parameter. The tag type represents a code for different data path applications. The tag parameter takes on multiple values based on the tag type.

Abstract: Techniques for efficient memory management that enable rapid longest prefix match lookups in memory. In general, the present invention is efficacious wherever maintenance of a good distribution of holes in a sorted list is required. This technique relies on a proactive hole management methodology to preserve a good distribution of holes in each memory region in such a way that one does not have to search for holes in order to insert or store a new entry into the list. In particular, all holes in a given region are kept in one or more contiguous sub-region. Keeping the holes contiguous requires a hole move every time there is a delete operation. The amortized cost of these operations is justified by the resulting simplification in later insert (store) and delete operations. For example, during an insert the new entry is placed at the end of the contiguous sub-region of used entries in the region.

Abstract: Methods and apparatus are disclosed for maintaining one or more ranges and identifying whether a value matches one of the ranges and optionally which range is matched. One implementation includes a range programming engine for generating one or more mapped subtrie values identifying each range, each of the mapped subtrie values identifying a different subset of the range. An associative memory stores the mapped subtrie ranges. A mapping engine receives a particular value and generates a lookup word including a mapped representation of the particular value. The associative memory performs a lookup operation to identify whether or not the particular value is within one of the ranges. In this manner, only a small number of associative memory entries are required to identify whether a mapped particular value falls within the range. The particular range matched can be identified such as by a read operation in an adjunct memory based on the address of the matching entry.

Abstract: Techniques for the efficient location of free entries for use in performing insert operations in a binary or ternary content addressable memory. As used in data communications and packet routing, such memories often rely on an organization that maintains entries of the same “length” within defined regions. The present invention keeps the free entries (holes) compacted into a contiguous subregion within each region, without requiring hole movement during deletes. These positive effects are accomplished by initially pre-filling the entire memory with a set of hole codes that each uniquely identify the holes in each region. A conventional memory write is then performed to load routing data into the memory. Typically, such routing information will not fill the entire memory, leaving unused entries (containing the region appropriate hole code) in each region. As entries need to be deleted, they are simply replaced by writing in the region-unique hole code.