Mechanism for running parallel application programs on metadata controller nodes
View Patent ↗The present invention is directed to a method for controlling file access in a multinode, shared storage, data processing system in which a one set of nodes is capable of acting as metadata controllers and a second set of nodes are tuned for running user applications. By providing two kinds of locks operative at the file level of granularity, a mechanism is produced which permits application programs to also run on their set of metadata controller nodes. One of the locks permits read and write access to existing data blocks but precludes operations such as file deletion or file truncation. The other lock is of lower authority and permits metadata controller nodes, which can provide time limited permissions to the application nodes, to withhold locks which authorize access when requests for access are made from application nodes.
1. A method for controlling file access in a multinode, shared storage data processing system in which a first set of nodes is capable of acting as metadata controller nodes and in which a second set of nodes has time limited file level access to said shared storage but which do not act as metadata controller nodes for said file, said method of control comprising the steps of:
issuing a first kind of lock for accessing said file, to at least one of the nodes in said first set, said first kind of lock permitting read and write access authority only to existing blocks of data within said file; and
issuing a lower authority lock, to at least one of the nodes in said second set, which authority permits nodes from said first set to withhold access authorizing locks for said second set when access is requested from a node in said second set.
2. The method of claim 1 in which said request for access is an initial request from a node in said second set.
3. The method of claim 1 in which said request is a renewal request made during said time limited access from a node in said second set.
4. The method of claim 1 further including the step of running a first application program on at least one node from said first set of nodes and a second application program on at least one of said second set of nodes wherein said first and second application programs both request access to said file.
5. The method of claim 4 in which said first application program both reads and writes from said file and in which said second application only reads from said file.
6. The method of claim 5 in which said second application program produces a visualization of data in said file as modified by said first application program.
7. A multinode, shared storage data processing system in which a first set of nodes is capable of acting as metadata controller nodes and a first node from said first set of nodes so acts to provide access to an individual file in said shared storage, said access being provided so that access occurs from a second node, not within said first set of nodes, which has time limited access to said file but which does not act as a metadata controller for said file, said data processing system including a memory within at least one of said nodes, said memory containing program code for performing the steps of: issuing a first kind of lock for accessing said file, to at least one of the nodes in said first set, said first kind of lock permitting read and write access authority only to existing blocks of data within said file; and issuing a lower authority lock, to at least one of the nodes in said second set, which authority permits nodes from said first set to withhold access authorizing locks for said second set when access is requested from a node in said second set.
8. A program product comprising a machine readable medium containing program code, for use in a multinode, shared storage data processing system in which a first set of nodes is capable of acting as metadata controller nodes and a first node from said first set of nodes so acts to provide access to an individual file in said shared storage, said access being provided so that access occurs from a second node, not within said first set of nodes, which has time limited access to said file but which does not act as a metadata controller for said file, said data processing system including a memory within at least one of said nodes for performing the steps of: issuing a first kind of lock for accessing said file, to at least one of the nodes in said first set, said first kind of lock permitting read and write access authority only to existing blocks of data within said file; and issuing a lower authority lock, to at least one of the nodes in said second set, which authority permits nodes from said first set to withhold access authorizing locks for said second set when access is requested from a node in said second set.