Netapp, Inc.

Network Appliance, Inc.

Tianyu Jiang

Richard Parvin Jernigan, Iv

Eric C Hamilton

Omprakaash C Thoppai

Ananthan Subramanian

Wesley R Witte

Ronald William Kownacki

Narayana R Tummala

Robert B Frangioso

The techniques introduced herein provide an efficient mechanism for reducing remote procedure requests to storage server nodes in a cluster of the storage servers to construct a directory path for a data container. According to one aspect of the invention, a new caching technique and an efficient organization of the cache memory are provided so that a cache memory on a storage server node is populated with individual path components of a directory structure. A novel cache invalidation mechanism is provided to maintain cache consistency at the cache so that when a path component changes, such as an identifier of a data container in the directory structure, and a path component is invalidated in the cache memory, the remaining path components can be retained and later reused.

Mechanism for distributed inode to path traversal in a striped volume system

A machine implemented process and system is provided. The process determines if any right granted to an entity for performing an I/O operation associated with a data container stored at a first storage volume is to be revoked. The right itself may be cached at the first storage volume and resident at a second storage volume. A recall message is sent to the node that manages the second storage volume. Any pending I/O operation is completed, after the message is sent and before the right is revoked. Thereafter, the right is revoked and the cached copies of the right are invalidated.

Method and system for revoking rights associated with I/O operations in storage systems

A computer data storage system is described. A processor maintains a striped volume set by striping a data container over a plurality of storage nodes. A storage node determines whether space available on that node is below a predetermined threshold, the predetermined threshold indicating a low-in-space state. The storage node sends a message indicating that the storage node is in a low-in-space state. The processor accepts no further write messages to the data container as long as the storage node is in a low-in-space state.

System and method for providing space availability notification in a distributed striped volume set

A method for operating a computer data storage system is disclosed. The system operates an active file system on a first volume of a plurality of volumes of storage devices connected to one or more servers, each volume being a plurality of storage devices. Snapshots of the active file system are stored on one or more destination volumes. A mirroring operation is initiated on a selected server of the one or more servers. A scanner executes on the selected server, the scanner identifying a latest snapshot on each of the one or more destination volumes, the scanner. Data blocks which are newer than a latest snapshot stored at each destination volume are sent to each destination volume.

Method and system for single pass volume scanning for multiple destination mirroring

A method and system for promoting a snapshot in a distributed striped volume system is provided. A master volume server is configured with a rollback process such that when it is determined that a rollback is required, the master volume server sets a flag persistently in its own raid label on disk. After the persistent flag is set, the master volume server determines a 'common snapshot,' and starts the process of sending RPC messages to each node hosting constituent volumes instructing each constituent volume to roll back to the identified snapshot. When the nodes receive this message a flag is set in the own raid label of each constituent volume and the volume then promotes the particular snapshot. If the master volume server has not received a successful response from each node that the snapshot promotion was successful within a specified time period, there is a retry. The common snapshot is then used as the active file system, thus providing data recovery for the striped volume set.

Method and system for promoting a snapshot in a distributed file system

A system and method for managing space availability in a distributed striped file system is provided. A master data server is configured to send space availability detection messages to a plurality of data volumes servers hosting constituent volumes of a striped volume set. If one of the constituent volumes in the striped volume set has a low-in-space flag set, then the master data volume instructs all of the constituent volumes to set a low-in-space required flag, and no further writes are accepted for the striped volume set. The low-in-space and low-in-space required flags represent two states, and these states are returned in response to subsequent space availability detection messages from the master data server. A procedure for utilizing reserved space to complete an accepted cross stripe write operation is also provided.

A cluster-wide published configuration system and method is provided for assigning host nodes to virtual interfaces (VIFs) in a cluster of data storage systems. A coordinating VIF manager publishes a set of failover rules using a replication database. The coordinating VIF manager monitors VIF hosting status within a cluster. In the event of a VIF failure, the coordinating VIF manager publishes a reassignment of host nodes using a single read-write transaction of a replication database service. Secondary VIF managers in the cluster must perform VIF hosting in accordance to the reassignment. If a secondary VIF manager can not activate an assigned VIF it must publishing new reassignment of VIF hosts via the replication database service.

System and method for virtual interface failover within a cluster

A system and method manages data versions in a file system. A data version field associated with a direct block pointer in each level 1 indirect block stores a data version associated with the data contained in the direct block. When data is modified subsequent to the creation of a persistent consistency point image, the data version is incremented to a next data version value to signify that the data has been modified. Replication is aided by the ease of identifying modified data blocks by examining the data version field associated with each block.

System and method for managing data versions in a file system

A method for operating a computer data storage system stores snapshots of an active file system of the storage system at a plurality of destinations. A latest snapshot stored at each destination of the plurality of destinations is identified. Those data blocks which are newer than the latest snapshot stored at the each destination are sent to the each destination. The active file system is scanned to find each data block newer than the oldest snapshot stored at a selected destination, and all such data blocks are tagged. Those data blocks which are tagged are sent to the selected destination.

A mirroring application running on a primary server in a multiple destination mirroring environment is provided. The mirroring application configures a scanner with snapshots that are registered. The scanner calculates a logical age for each snapshot. The scanner scans a flexible volume once for data blocks that are newer than a predetermined snapshot. The scanner tags each such block with a logical age that is equivalent to the oldest snapshot that refers to that block. The scanner loads the tagged blocks in a queue. A sender module associated with each destination in the mirroring environment inspects blocks in the queue and retrieves only those blocks younger than a destination reference snapshot. The sender sends those blocks to the destination and filters out older blocks, thus bringing the destination mirror up to date with the current active file system.

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Export, PA, United States of America

Tianyu Jiang