Netapp, Inc.

Network Appliance, Inc.

David Brittain Bolen

Susan M Coatney

Vijayan Rajan

Brian Christopher Parkison

Jeffrey S Kimmel

John T Lloyd

Ling Zheng

Douglas P Doucette

Loellyn Jane Cassell

John Meneghini

Anshul Pundir

David W Minnich

Mohan Srinivasan

Blake H Lewis

Ashish Prakash

Rithin Kumar Shetty

Brian J Pawlowski

Amol Chitre

Guillermo Roa

Suhas Prakash

Kiran Kanakadandi

Adarsh Seetharam

Brian Pawlowski

A snap restore technique efficiently restores snapshots of storage containers served by a storage input/output (I/O) stack executing on one or more nodes of a cluster. A Small Computer Systems Interface administration layer interacts with a volume layer of the storage I/O stack to manage and implement a snap restore procedure to restore one or more snapshots of a storage container. The storage container may be a logical unit (LUN) embodied as parent volume (active volume) and the snapshot may be represented as an independent volume embodied as read-only copy of the active volume. The snap restore procedure may be configured to allow restoration to a single snapshot of a LUN or restoration of a plurality of LUNs organized as a consistency group from a group of snapshots. Restoration of the LUN from a snapshot involves (i) creation of another independent volume embodied as a read-write copy (clone) of the snapshot, (ii) replacement of the (old) active volume with the clone, (iii) deletion of the old active volume, and (iv) mapping of the LUN to the clone (i.e., a new active volume).

Snapshot restore workflow

A technique enables recovery of storage space trapped in an extent store from overlapping write requests associated with metadata describing volume logical storage addresses for data in the extent store. The metadata is organized as metadata entries in a multi-level dense tree metadata structure. When a level of the dense tree is full, the metadata entries of the level are merged with a next lower level of the dense tree in accordance with a dense tree merge operation. The technique may be invoked during the merge operation to process the metadata entries associated with the overlapping write requests involved in the merge operation. Processing of the overlapping write requests during the merge operation may partially overwrite extents which, in turn, may result in logical storage space being trapped in the extent store. The technique may perform read-modify-write (RMW) operations on the partially overwritten extents to recapture that trapped space.

Technique for recovery of trapped storage space in an extent store

Various computing components (such as devices, operating environments, and processes) may communicate by exchanging instances of a data collection, such as a class or data structure. However, the definition of the data collection may evolve to specify different numbers, types, properties, and orderings of the items in the data collection, and it may be difficult to verify the structure and contents of an instance received from another component and possibly of a different version. This difficulty may be mitigated by exchanging versioning information about the instance (e.g., as part of the communications wire protocol) and by allocating the converting such that the sender may downconvert to earlier versions requested by a recipient, while the recipient may upconvert to later versions than a version provided by a sender. These techniques may promote the accuracy and consistency of information exchange among many components that operate on different versions of the data collection.

Automated conversion of versioned data collections

A method for operating a computer storage system maintains a client computer interacting with the storage system, the client computer storing data on a data storage device of the computer storage system. Locating, by a client-side agent executing on the client computer that examines metadata of the client computer, one or more sets of blocks allocated and then deleted, hereinafter referred to as deleted blocks, within the computer storage system. Sending a command to the storage system, the command to identify the deleted blocks within the computer storage system. Deallocating, in response to receiving the command, the identified deleted blocks within the computer storage system.

System and method for reclaiming unused space from a thinly provisioned data container

A system and method for lun migration between data containers, such as aggregates of a storage system is provided. A new destination lun is created on a destination aggregate. A background copy process is then started that copies all data from a source lun on a source aggregate to the destination lun. The storage system continues to process client-originated data access requests directed to the source lun while the background copying continues. Once all the data of the source lun has been copied to the destination lun, processing of data access requests to the lun(s) is quiesced by the storage system. Lun maps of the storage system are then updated and processing of the client-originated data access requests is resumed with those requests now being directed to the destination lun.

System and method for migrating lun data between data containers

A system and method provides a single system image for a clustered storage network including techniques for processing data access commands between storage appliances over the cluster interconnect. The system is configured such that the cluster is assigned a single world wide nodename. Requests coming to the cluster from client initiators are directed to one or the storage appliances in the cluster, i.e. the 'receiving' storage appliance. Commands received by the receiving storage appliance are examined to determine LUN value(s) in the request. If the LUN value is associated with a local storage device, the request is processed by the receiving storage appliance. If the LUN value is not associated with the receiving storage appliance, the request is conveyed over the cluster interconnect to the partner storage appliance to be processed and the appropriate data written or retrieved.

Single nodename cluster system for fibre channel

Techniques introduced here swap logical unit meta-data of a logical unit without offlining the logical unit. In accordance with the techniques, a connection between a network storage controller and a host for the logical unit is maintained while meta-data of the logical unit are swapped with another logical unit available to the network storage controller. The swapping substitutes one logical unit for another without disconnecting the host. Advantageously, the host is not required to perform operations to re-establish a connection. Various software and hardware units can implement the techniques described herein.

Method and system for logical unit substitution

A system and method for allowing more rapid takeover of a failed filer by a clustered takeover partner filer in the presence of a coredump procedure (e.g. a transfer of the failed filer's working memory) is provided. To save time, the coredump is allowed to occur contemporaneously with the takeover of the failed filer's regular, active file service disks by the partner so that the takeover need not await completion of the coredump to begin. This is accomplished, briefly stated, by the following techniques. The coredump is written to a single disk that is not involved in regular file service, so that takeover of regular file services can proceed without interference from coredump. A reliable means for both filers in a cluster to identify the coredump disk is provided, which removes takeover dependence upon unreliable communications mechanisms. A means is provided for identification during takeover of the coredump disk and SCSI-3 reservations are employed to coordinate write access to (ownership of) shared disks, so as to prevent takeover from interfering with coredump while simultaneously preventing the failed filer is from continuing to write regular file system disks being taken over by its partner.

System and method for takeover of partner resources in conjunction with coredump

This invention provides a system and method for selecting and communicating a single disk (a 'coredump disk') for use in a coredump procedure by a failed file server (or filer). A selection method on the failed filer determines the 'best candidate' coredump disk according to a predetermined set of criteria. For example, the available disks that can receive coredump data are located and ordered so as to prefer disks that best match the coredump data size requirement, are least likely to be needed for normal service by the server; and require the least preparation to receive coredump data. Appropriate attributes on the selected coredump disk are written to indicate that a coredump is in progress, and the location of the coredump data. Upon reboot of the failed filer (or takeover by a cluster partner), the coredump disk is identified and the coredump data recovered by reading back appropriate attributes.

System and method of selection and communication of a disk for storage of a coredump

A technique enables application data stored on storage devices of a storage system to be accessible by a client as either a file or logical unit number (lun). The storage system is illustratively embodied as a multi-protocol storage appliance having a storage operating system that implements a file system. The file system logically organizes the application data as a virtual disk (vdisk) comprising a plurality of inodes including a prefix stream inode, a lun inode (storing the application data) and a suffix stream inode. The prefix and suffix stream inodes allow the vdisk to be shared over a block-based protocol or a file-based protocol by enabling apportionment of client operating system dependent storage device contents from application data contents of the vdisk.

System and method for supporting file and block access to storage object on a storage appliance

System and method for takeover of partner re-sources in conjunction with coredump

A method of operating a storage server includes executing a process of restoring a data set in an active file system of the storage server from a persistent point-in-time image of a data set, and during the process of restoring the data set, servicing input/output requests directed at the data set by a client of the storage server.

Method and apparatus for restoring a data set

A system and method for reclaiming unused space from a thinly provisioned data container served by a storage system. A host-side agent detects blocks of the data container that may be freed and sends a novel Punch Hole command to the storage system associated with the data container. The storage system allocates the appropriate blocks in response to the Punch Hole command.

A system and method for throttling data access rates through data containers prevents starvation of storage system resources by active clients. A SCSI throttle module of a storage operating system of storage system determines if the number of outstanding access requests associated with the client or initiator group exceeds a preset throttle value.

Growing community of inventors

Durham, NC, United States of America

David Brittain Bolen