Methods to perform disk writes in a distributed shared disk system needing consistency across failures

A non-transitory computer-readable storage medium carrying instructions, which when executed by one or more processors of a first node of a plurality of nodes, wherein each of the plurality of nodes has write access to a shared persistent storage to write data items to the shared persistent storage, and wherein a writing of data items to the shared persistent storage by the plurality of nodes is coordinated by one or more masters, cause:

• writing a data item in a cache associated with the first node to the shared persistent storage;
• and
• while the writing of the data item is in progress and before the writing of the data item completes:
• initiating a transfer operation to transfer the data item and a lock associated with the data item from the first node to a second node, wherein the lock allows the second node to modify the data item;
• and
• sending a communication to a master of the data item to inform the master that writing of the data item to the shared persistent storage is in progress, wherein the one or more masters comprises the master.

A method performed by a first node of a plurality of nodes, wherein each of the plurality of nodes has write access to a shared persistent storage to write data items to the shared persistent storage, and wherein a writing of data items to the shared persistent storage by the plurality of nodes is coordinated by one or more masters, comprising:

• transferring a data item and a lock associated with the data item from the first node to a second node, wherein the lock has a current role associated therewith of local or global, wherein a local role indicates that the data item associated with the lock can be written to the shared persistent storage without communicating with a master of the data item, and a global role indicates that the data item associated with the lock cannot be written to the shared persistent storage without first communicating with the master of the data item, wherein the one or more masters comprises the master, and wherein transferring comprises:
• determining whether the data item has been dirtied by the first node;
• in response to determining that the data item has been dirtied by the first node, transferring the data item and the lock associated with the data item to the second node with a role of global assigned to the lock;
• and
• in response to determining that the data item has not been dirtied by the first node, and that the current role associated with the lock is local, transferring the data item and the lock associated with the data item to the second node with a role of local assigned to the lock.

A non-transitory computer-readable storage medium carrying instructions, which when executed by one or more processors of a first node of a plurality of nodes, wherein each of the plurality of nodes has write access to a shared persistent storage to write data items to the shared persistent storage, and wherein a writing of data items to the shared persistent storage by the plurality of nodes is coordinated by one or more masters, cause the one or more processors to perform:

• transferring a data item and a lock associated with the data item from the first node to a second node, wherein the lock has a current role associated therewith of local or global, wherein a local role indicates that the data item associated with the lock can be written to the shared persistent storage without communicating with a master of the data item, and a global role indicates that the data item associated with the lock cannot be written to the shared persistent storage without first communicating with the master of the data item, and wherein transferring comprises:
• determining whether the data item has been dirtied by the first node;
• in response to determining that the data item has been dirtied by the first node, transferring the data item and the lock associated with the data item to the second node with a role of global assigned to the lock;
• and
• in response to determining that the data item has not been dirtied by the first node, and that the current role associated with the lock is local, transferring the data item and the lock associated with the data item to the second node with a role of local assigned to the lock.