Network Appliance, Inc.

Netapp, Inc.

Auspex Systems, Inc.

David Hitz

James Lau

Michael A Malcolm

Byron Rakitzis

John K Edwards

Steven Robert Kleiman

Guy Harris

Sean W O'Malley

Blake H Lewis

Allan Schwartz

Norman Hutchinson

Mark Muhlestein

James J Voll

Yu-Ping Cheng

Steven H Rodrigues

Daniel Ting

Mehul S Shah

Andrea Borr

Robert Hawley

Joan Pearson

Integrating a file system with a RAID array that exports precise information about the arrangement of data blocks in the RAID subsystem. The present invention uses separate current-write location (CWL) pointers for each disk in the disk array where the pointers simply advance through the disks as writes occur. The present invention writes on the disk with the lowest CWL pointer. A new disk is chosen only when the algorithm starts allocating space for a new file, or when it has allocated N blocks on the same disk for a single file. A sufficient number of blocks are defined as all the buffers in a chunk of N sequential buffers in a file. The result is that CWL pointers are never more than N blocks apart on different disks, and large files have N consecutive blocks on the same disk.

Allocating files in a file system integrated with a RAID disk sub-system

A plurality of types of volumes are maintained, a volume being a logical arrangement of storage space on one or more data storage devices. A volume type field is used to designate the type of a particular volume, and a flexible volume paradigm is selected by the volume type field for interpreting data within a data structure written to a data storage device of the one or more data storage devices. A physical volume block number to virtual volume block number mapping pair (pvbn/vvbn pair) is designated by the volume type field, the pvbn/vvbn pair is used to translate a physical volume block number to a virtual volume block number. A request to write a data to a first block of the particular volume is received, a pvbn/vvbn pair is determined. The data is written to the physical block designated by the pvbn/vvbn pair.

System and method for enabling a storage system to support multiple volume formats simultaneously

A method and apparatus for operating a data storage system is disclosed. An original active file system holds incoming write transactions. Data is written at a selected time to blocks in a data storage device of the original active file system, the data written to blocks which do not hold old data of the data storage system. Pointers to data of the original active file system are written at the selected time to the data storage device, the pointers written to blocks which do not hold old data of the data storage system, the pointers and a previously saved data of the active file system forming a consistency point of the original active file system at the selected time. A new active file system is started using the consistency point of the original active file system at the selected time.

Multiple concurrent active file systems

Maintenance of plural active file systems, wherein each of the active file systems initially access data shared with another of the active file systems, and wherein changes made to each of the active file systems are not reflected in other active file systems. When a second active file system is created based on a first active file system, the first active file system and the second active file system initially share data. When changes are made to the first active file system, modified data is recorded in the first active file system in a location that is not shared with the second active file system. When changes are made to the second active file system, modified data is recorded in the second active file system in a location that is not shared with the first active file system. Also, creation of the plural active file systems.

A system and method enables a storage system to support multiple volume type simultaneously. A volume type field is contained within a file system information block that permits the storage system to determine the type of volume of a particular volume associated therewith. The storage operating system may then interpret various on-disk data structures in accordance with the appropriate volume type.

Allocating files in a file system integrated with a raid disk sub-system

In a technique for compressing data, a data storage server receives a set of data, which includes a first number of subsets. The storage server defines a number of compression groups for the set of data, each compression group including multiple entries, each entry containing a pointer to a different subset of the set of data. At least part of the set of data is then compressed into a smaller number of subsets. For each of the subsets which does not contain compressed data after the compression, a predetermined value is stored in the corresponding entry of the corresponding compression group, to indicate that corresponding data is compressed and represented elsewhere in the compression group. The predetermined value may also indicate which compression algorithm was used to compress the data.

In a data storage server, for each subsets which does not contain compressed data after the compression, a predetermined value is stored in the corresponding entry of the corresponding compression group to indicate that corresponding data is compressed

The invention provides a method and system for duplicating all or part of a file system while maintaining consistent copies of the file system. The file server maintains a set of snapshots, each indicating a set of storage blocks making up a consistent copy of the file system as it was at a known time. Each snapshot can be used for a purpose other than maintaining the coherency of the file system, such as duplicating or transferring a backup copy of the file system to a destination storage medium. In a preferred embodiment, the snapshots can be manipulated to identify sets of storage blocks in the file system for incremental backup or copying, or to provide a file system backup that is both complete and relatively inexpensive. Also in a preferred embodiment, shadow snapshots can be maintained, with a shadow snapshot including a set of member storage blocks that formed a consistent file system other than an active file system, with a set of selected member storage blocks removed from the consistent file system.

File system image transfer

A method of determining a configuration of a collection of storage units, includes: generating a configuration, identifying for a specific configuration by use of a configuration identifier; and assigning the specific configuration to the first labels of all storage units and then to the second labels of all storage units, and utilizing the configuration identifier to determine the most recent configuration successfully written to all disks in the configuration.

Raid assimilation method and apparatus

The invention provides techniques for duplicating all or part of a file system while maintaining consistent copies of the file system. A preferred embodiment reads data from the source file system (mapped according to a first storage block arrangement) creates an image stream and writes this data onto the destination file system (in accordance with a second storage block arrangement). Thus, the invention allows an image transfer between file systems that have dissimilar characteristics. An intermediate storage medium can be used to store or transmit the data read from the source file system before writing the data to the destination file system. (For example, the intermediate storage medium can include a magnetic tape or other archival device, or a network.) Another aspect of the invention writes the data to the intermediate storage medium using a normalized or implied block list. The information is read from the intermediate storage medium using normalized or implied block list and written to the destination file system according to the second storage block arrangement. Another aspect of the invention is that the invention determines a first set of block numbers (BNs), determines where the blocks referenced by these BNs are to be stored, and updates the BNs accordingly.

File system image transfer between dissimilar file systems

The present invention is a method for providing error correction for an array of disks using non-volatile random access memory (NV-RAM). Non-volatile RAM is used to increase the speed of RAID recovery from a disk error(s). This is accomplished by keeping a list of all disk blocks for which the parity is possibly inconsistent. Such a list of disk blocks is much smaller than the total number of parity blocks in the RAID subsystem. The total number of parity blocks in the RAID subsystem is typically in the range of hundreds of thousands of parity blocks. Knowledge of the number of parity blocks that are possibly inconsistent makes it possible to fix only those few blocks, identified in the list, in a significantly smaller amount of time than is possible in the prior art. The technique for safely writing to a RAID array with a broken disk is complicated. In this technique, data that can become corrupted is copied into NV-RAM before the potentially corrupting operation is performed.

Providing parity in a RAID sub-system using non-volatile memory

The present invention provides a method for keeping a file system in a consistent state and for creating read-only copies of a file system. Changes to the file system are tightly controlled. The file system progresses from one self-consistent state to another self-consistent state. The set of self-consistent blocks on disk that is rooted by the root inode is referred to as a consistency point. To implement consistency points, new data is written to unallocated blocks on disk. A new consistency point occurs when the fsinfo block is updated by writing a new root inode for the inode file into it. Thus, as long as the root inode is not updated, the state of the file system represented on disk does not change. The present invention also creates snapshots that are read-only copies of the file system. A snapshot uses no disk space when it is initially created. It is designed so that many different snapshots can be created for the same file system. Unlike prior art file systems that create a clone by duplicating the entire inode file and all of the indirect blocks, the present invention duplicates only the inode that describes the inode file. A multi-bit free-block map file is used to prevent data from being overwritten on disk.

Copy on write file system consistency and block usage

A is a method is disclosed for integrating a file system with a RAID array that exports precise information about the arrangement of data blocks in the RAID subsystem. The file system examines this information and uses it to optimize the location of blocks as they are written to the RAID system. Thus, the system uses explicit knowledge of the underlying RAID disk layout to schedule disk allocation. The method uses separate current-write location (CWL) pointers for each disk in the disk array where the pointers simply advance through the disks as writes occur. The algorithm used has two primary goals. The first goal is to keep the CWL pointers as close together as possible, thereby improving RAID efficiency by writing to multiple blocks in the stripe simultaneously. The second goal is to allocate adjacent blocks in a file on the same disk, thereby improving read back performance. The method satisfies the first goal by always writing on the disk with the lowest CWL pointer. For the second goal, a new disks chosen only when the algorithm starts allocating space for a new file, or when it has allocated N blocks on the same disk for a single file. A sufficient number of blocks is defined as all the buffers in a chunk of N sequential buffers in a file. The result is that CWL pointers are never more than N blocks apart on different disks, and large files have N consecutive blocks on the same disk.

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Los Altos, CA, United States of America

David Hitz