Netapp, Inc.

Sun Microsystems, Inc.

Emc Corporation

Stanley Luke

Randall David Smith

Ravikanth Dronamraju

Aamir Rashid

Nils Wygant

David A Grunwald

Howard Hall

Arun Dugganapally

Milan Merhar

Christopher Cochrane

Stephen Ferrari

Mitchell Condylis

Vaibhav Nivargi

Servicing an access request using a plurality of replicas of data includes determining which of the replicas are available and selecting one of the replicas for servicing the access request based on which of the replicas are available. At least one other replica is indicated as not available in response to receiving a monitoring message indicating that the at least one other replica is subject to degraded performance. The monitoring messages are independent of the access request. The monitoring messages may be SNMP messages. Servicing an access request using a plurality of replicas of data may also include determining if each of the SNMP messages affects the availability of the replicas. The replicas may be selected in round robin fashion or randomly.

Automated load balancing

An updateable list is provided for use in mounting a storage volume. Such list may include a plurality of block references capable of being used to access corresponding blocks required for mounting the storage volume. In use, such list may be utilized for accessing the blocks in a more efficient manner, by accessing a plurality of such blocks in parallel, as well as performing the block accessing and storage volume mounting in parallel.

System and method for mounting a storage volume utilizing a block reference list

Data-storage volumes, such as a file system on a storage system, may utilize a particular operating system format. Converting a data-storage volume to a different format may be desirable at times. However, this can be time consuming and resource intensive if data needs to be copied. Accordingly, substantially copying-free, in-place conversion of a data-storage volume from a first format to a second format is provided herein. In one embodiment, a data-storage volume may be converted from a first format to a second format while the data-storage volume is mounted and/or without copying data within the data-storage volume to a separate data-storage volume. Before conversion, features associated with the first format and the second format may be compared to detect incompatibilities that may result from conversion. During conversion, access to the data-storage volume may be blocked. Upon successful conversion, various post conversion operations may be performed.

Volume format conversion

Data storage volumes, such as a file system on a storage system, may utilize a particular operating system format. Converting a volume to a different format may be desirable at times. However, this can be time consuming and resource intensive if data needs to be copied. Accordingly, substantially copying-free, in-place conversion of a data-storage volume from a first format to a second format is provided herein. In one embodiment, it is determined whether the volume can be converted, for example, by comparing compatibility of features between the first and second formats. A desired feature list is retrieved and respective features are checked for compatibility. Access to the volume is blocked during the conversion, and the volume is converted if the features are found to be compatible. If the conversion is successful, post conversion operations are performed, including unblocking the volume and notifying clients that the volume is available for access.

On or more techniques and/or systems are provided for rapidly resuming processing of client requests after a system failure event. Accordingly, during a boot-up process, a storage system, upon detecting a system failure event of the storage system, conditions its system memory to reflect a state of the system memory at a time of the failure by processing client requests or commands stored in a non-volatile operations log. The storage system can resume processing client requests after processing the operations in the nonvolatile operations log and prior to flushing data to storage devices.

Recovering from a system failure

A method and apparatus for delaying the process of freeing data blocks during the processing of a non-volatile transactions log are disclosed. Accordingly, after a system failure, when a storage system is replaying transactions in a non-volatile transactions log, the storage system flushes the data generated from the transactions to disk storage without freeing and data blocks which, as a result of processing the transactions log, are no longer storing data that is part of the active file system. Consequently, the replay of the transactions log takes less time, and the storage system is brought online more quickly.

Storage system and method for rapidly recovering from a system failure

An apparatus and method for rapidly resuming the processing of client requests after a system failure event are disclosed. Accordingly, a surviving storage system, upon detecting a system failure event at a partner storage system, executes a takeover routine and conditions its system memory to reflect the state of the system memory of the failed storage system by processing client requests or commands stored in an operations log mirror. Then, the storage system converts the unused portion of the log mirror for use as an operations log, and resumes processing client requests prior to flushing any data to storage devices.

Surviving storage system takeover by replaying operations in an operations log mirror

Methods and systems consistent with certain aspects related to the present invention provide a digital network having a plurality of data storage elements, at least one client, and a switch element. The switch element may be operable to receive access requests from the client and provide access to data on the storage elements in response to one or more access requests.

Growing community of inventors

Stow, MA, United States of America

Stanley Luke