Abstract: A method for detecting communication failures on a network comprising a server computer connected to multiple client computers, said server and client computers communicating through the transmission of data packets via the network. The method includes the step of periodically sending an echo request message from the server computer to the client computers. Each client computer, following receipt of the echo request message, sends an echo reply message back to the server computer. The method further includes the steps of monitoring the rate at which data packets are received by the server computer; and reducing the frequency at which echo request messages are sent from the server computer to the client computers during periods when the rate at which data packets are received by the server computer exceeds a re-configurable rate value. The frequency at which the echo request messages are sent is dependent upon the rate at which data packets are received by said server computer.

Abstract: An improved file system for managing data storage and retrieval in a clustered UNIX computer system including a plurality of processing nodes and an interconnection network connecting the processing nodes. The improved file system includes a data storage device, such as a disk storage unit, connected via a shared SCSI interconnect with each one of the processing nodes, rather than connected directly with a single processing node. The structure layout for the file system, which is maintained on the data storage device, includes sufficient information to enable all of the processing nodes to access said file system.

Abstract: A method for identifying and repairing file system damage following the failure of a processing node within a clustered UNIX file system including a plurality of processing nodes, an interconnection network connecting the processing nodes, and a data storage device connected via a shared interconnect with each one of the plurality of processing nodes. The method includes the step of maintaining a journal for each processing node, each journal containing a bit map identifying inodes to which its associated processing node has acquired and retains an exclusive right. Each bit map journal is updated whenever its associated processing node acquires an exclusive right to an inode. Following a failure of a processing node, a non-failed processing node is designated to audit the inodes associated with the failed node. Auditing is accomplished by reading the bit map journal associated with the failed processing node and obtaining the exclusive right to every inode found within the journal.