Sun Microsystems, Inc.

Anil Swaroop

Yousef A Khalidi

Siamak Nazari

Srinivasan Viswanathan

Madhusudhan Talluri

David Dion

A file disaster recovery system that employs geographical replication of data from a local site to remote site in a such a manner that file requests from clients of the local site can be handled by a file server on the remote site following a failover from the local site to the remote site. Geographical data replication software running on a local server checkpoints to a log in local stable storage all information on file operations that change the file state of the local file system. According to a selected mode, the local geographical data replication software flushes information in the log pertaining to the file operations since the last flush to the remote site. At the remote site, compatible remote geographical data replication software running on a remote file server receives the flushed log and replicates in sequence order the file operations represented in the flushed log. The results of the operations are stored on remote stable storage. The local and remote servers can be clusters or single servers. There is no need for commonality, except for operating and file systems, between the local and remote sites. Because operations are replicated and not low level, formatted data, the local and remote stable file storage can be completely different.

Method and apparatus for file system disaster recovery

A system and method are disclosed that provides transparent, global access to devices on a computer cluster. The present system generates unique device type (dev.sub.-- t) values for all devices and corresponding links between a global file system and the dev.sub.-- t values. The file system is modified to take advantage of this framework so that, when a user requests that a particular device, identified by its logical name, be opened, an operating system kernel queries the file system to determine that device's dev.sub.-- t value and then queries the a device configuration system (DCS) for the location (node) and identification (local address) of a device with that dev.sub.-- t value. Once it has received the device's location and identification, the kernel issues an open request to the host node for the device identified by the DCS. File system components executing on the host node, which include a special file system (SpecFS), handle the open request by returning to the kernel a handle to a special file object that is associated with the desired device. The kernel then returns to the requesting user a file descriptor that is mapped to the handle, through which the user can access the device.

System and method for transparent, global access to physical devices on

A system and method are disclosed for rendering devices on a cluster globally visible, wherein the cluster includes a plurality of nodes on which the devices are attached. The system establishes for each of the devices in the cluster at least one globally unique identifier enabling global access to the device. The system includes a device registrar that creates the identifiers and a global file system. The identifiers include a globally unique logical name by which users of the cluster identify the device and a globally unique physical name by which the global file system identifies the device. The registrar creates a one-to-one mapping between the logical name and the physical name for each of the devices. The system also includes a device information (dev.sub.-- info) data structure maintained by the device registrar that represents physical associations of the devices within the cluster. Each association corresponds to the physical name of a device file maintained by the global file system. The device registrar determines for an attached device a globally unique, device type (dev.sub.-- t) value; creates dev.sub.-- info data structure entry and a corresponding physical name; generates a logical name based on the dev.sub.-- t value and the physical name; and associates the dev.sub.-- t value with the device file representing the attached device. Given this framework, a user of the cluster can access any of the devices by issuing the global file system an access request identifying the device to be accessed by its logical name.

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Loma Linda, CA, United States of America

Anil Swaroop