International Business Machines Corporation

Felipe Knop

Frank Bernhard Schmuck

Chun-Shi Chang

John Robert Hare

Tseng-Hui Lin

Myung Mun Bae

Owen Theodore Anderson

Enci Zhong

Paul D Moyer

Alessandro Sorniotti

Deepavali M Bhagwat

Yuri L Volobuev

John Lewars

James C Davis

Dennis Duane Jurgensen

Anil Kurmus

Willard A Davis

Robert K Gardner

Hai Zhong Zhou

Johannes Sayre

Abhishek Jain

Douglas J Griffith

Soumitra Sarkar

Yi Zhou

Marcos Nogueira Novaes

Christopher V Derobertis

Roger Lee Haskin

Theodore Brian Vojnovich

Shah Mohammad Rezaul Islam

Orvalle Theodore Kirby

Gregory D Laib

Robert J Curran

Thomas K Clark

Sudhir Gurunandan Rao

D Scott Guthridge

Thomas V Weaver

Ronald T Goering

Steven R Champagne

George Sohos

Serban C Maerean

Sameh Afif Fakhouri

Huzefa Pancha

Robert R Gensler, Jr

Hemant R Suri

Timothy L Race

Lyle Gayne

Olaf Weiser

John Hare

Robert Gensler

Hemant Suri

A computer-implemented method, according to one embodiment, includes causing a memory assessment thread to perform a first predetermined node memory contention state determination sequence for a predetermined first node. The first predetermined node memory contention state determination sequence includes recording a first timestamp, and allocating dedicated memory of the predetermined first node. The first predetermined node memory contention state determination sequence furthermore includes attempting to fill the allocated memory with content subsequent to recording the first timestamp, and recording a second timestamp after attempting to fill the allocated memory. The method further includes determining a first memory contention state of the predetermined first node based on results of performing the first predetermined node memory contention state determination sequence. The determined first memory contention state is caused to be included in a first type of message sent to a second node.

Determining a memory contention state of a node

Provided are a computer program product, system, and method for switching serialization techniques for handling concurrent write requests to a shared file. A first node serializes write requests from client nodes to write to the shared file. The first node determines whether to switch to a second node to manage write quests to the shared file based on a pattern of write requests to the shared file. The client nodes are notified to direct write requests to the shared file to the second node in response to determining to switch to the second node. The second node processes write requests to the shared file to serialize writes to the shared file after the client nodes are notified to submit the write requests to the shared file to the second node.

Switching serialization techniques for handling concurrent write requests to a shared file

A method for executing operation requests includes formatting one or more storage devices and selecting one or more labeled replicas and one or more distinguished replicas, receiving an operation request with respect to a set of data blocks, identifying a preferred replica corresponding to the received operation request, determining whether the replication-pending bits for the preferred replica are set, and executing the received operation request with respect to the corresponding distinguished replica. A method for executing a write operation request additionally includes setting replication-pending bits with respect to the labeled replica, wherein the replication-pending bits indicate an incomplete write request, writing data to both a labeled replica and a distinguished replica, and clearing the replication-pending bits with respect to the labeled replica to indicate the completion of the write operation. A method for executing a read operation additionally includes identifying a preferred replica with respect to the received read request.

Interrupted replicated write recognition

A method and a computer system for asymmetric replication of data are provided. Storage of a set of data is organized as a first copy and as a second copy in non-volatile storage. The second copy is reliable and stored so as to be readable at a speed slower than for the first copy. A read instruction regarding the set of data is received and performed preferentially via the first copy such that the asymmetric replication achieves enhanced performance speed. A request to execute a write operation is received. The write operation is executed to the first copy and to the second copy. In response to determining that the write operation to the first copy was unsuccessful, a label for the first copy is set as stale.

Efficient use of optional fast replicas via asymmetric replication

Aspects include testing distributed file systems by selecting a file in a multiple writer environment and selecting an offset of a block in the file. Test data is generated for the block by randomly selecting a starting value from a plurality of possible starting values. A test header that includes the starting value and a test data sequence that starts with the starting value is created. A file system that is being tested writes the test header and the test data sequence to the block. Contents of the block are read by the file system that is being tested, and expected contents of the data sequence are determined based on contents of the read header. The expected contents of the data sequence are compared to the read data sequence and an error indication is output based on the expected contents not being equal to the read contents.

Detection of file corruption in a distributed file system

A computer-implemented method of encryption of several units of a computerized system, wherein each of the units comprises data, includes generating distinct initialization vectors, or IVs, for the units, and storing the generated IVs; and for each unit of the several units: accessing a stored IV corresponding to the unit; and encrypting the unit according to the accessed IV and an encryption key.

Initialization vectors generation from encryption/decryption

A system to improve communication security in cluster machine processing may include interconnected computers that can jointly process data. The system may also include a shared secret key used by each of the interconnected computers to encrypt, decrypt, and/or authenticate data being sent, or received, from one of the interconnected computers to another of the interconnected computers. The system may further include a new shared secret key used by each of the interconnected computers to encrypt, decrypt, and/or authenticate data being sent, or received, from one of the interconnected computers to another of the interconnected computers. In addition, the new shared secret key may coexist with the shared secret key without adversely affecting the joint processing of data performed by the plurality of interconnected computers.

Secure communications in computer cluster systems

A method is provided for establishing clusters in a distributed data processing environment having a plurality of nodes. The frequency of messages sent for the purpose of cluster formation is selected based on ranking of the nodes. Higher ranking nodes transmit such messages more frequently than lower ranking nodes. Lower ranked nodes thus are provided with an opportunity to join a cluster without first having to transmit their own messages to effectuate the joining.

Cluster bring-up in a distributed topology liveness system

A system, method and computer readable medium are provided for configuring network interfaces grouped into nodes for monitoring functionality. According to the method, a base address and subnet mask for the network interfaces are received, and a monitoring address is automatically generated for each of the network interfaces based on the base address, the subnet mask, and the nodes. The monitoring addresses is generated such that the monitoring address for each of the network interfaces is on a different subnet than the monitoring addresses for all of the other network interfaces in the same node as that network interface. Additionally, the monitoring addresses are assigned to the network interfaces for use by the monitoring process, with each of the monitoring addresses being assigned by being added as an additional network interface address of its network interface. Also provided is a method for monitoring functionality of network interfaces and providing fault recovery.

Automatic configuration of network for monitoring

The acquisition of a lock among nodes of a divided cluster is disclosed. A method is performable by each of at least one node of the cluster. A node waits for a delay corresponding to its identifier. The node asserts intent to acquire the lock by writing its identifier to X and Y variables where another node has failed to acquire the lock. The node waits for another node to acquire the lock where the other node has written to X, and proceeds where Y remains equal to its own identifier. The node waits for another node to acquire the lock where the other node has written to a Z variable, and writes its own identifier to Z and proceeds where the other node has failed. The node writes a value to Y indicating that it is acquiring the lock, and maintains acquisition by periodically writing to Z.

Lock acquisition among nodes of divided cluster

A method for communicating node liveness in a multinode data processing system employs an operating system function that provides a degree of self-awareness in 'sensing' an imminent but still pending failure as the basis for providing special flag signals over a channel which employs nonvolatile storage in a heartbeat signaling path.

Fast node failure detection via disk based last gasp mechanism

The determination of node and/or adapter liveness in a distributed network data processing system is carried out via one messaging protocol that can be assisted by a second messaging protocol which is significantly less susceptible to delay, especially memory blocking delays encountered by daemons running on other nodes. The switching of protocols is accompanied by controlled grace periods for needed responses. This messaging protocol flexibility is also adapted for use as a mechanism for controlling the deliberate activities of node addition (birth) and node deletion (death).

Computer program product using two different programs to determine state of a network node to eliminate message response delays in system processing

A system, method and computer readable medium are provided for monitoring functionality of multiple network interfaces and providing fault recovery. The network interfaces are grouped into nodes and a monitoring address is assigned to each of the network interfaces such that the monitoring address for each of the network interfaces is on a different subnet than the monitoring addresses for all of the other network interfaces in the same node as that network interface. According to the method, each of the network interfaces is assigned one or more recovery addresses that each are different than its monitoring address. A monitoring message is periodically sent to each of the network interfaces via the monitoring addresses in order to determine the functionality of the network interfaces. If no monitoring message is received within a predetermined period, a recovery operation is performed for one of the network interfaces using one or more recovery addresses of the one network interface.

System and method for monitoring the functionality of network interfaces

Growing community of inventors

Poughkeepsie, NY, United States of America

Felipe Knop