Distributed file system

摘要

A distributed file system for devices is described. In an embodiment, each data element stored on one of the devices has an associated location and availability attribute. The location attribute is stored co-located with the data element. The availability attribute and a copy of the location attribute are stored by a metadata service. When a client on a device needs to access a data element, it sends a request to the metadata service to find the location of the data element. If the data element is available, this information is provided to the client and this may involve waking a dormant device which holds the data element. Where the data element is not available, read only access may be granted to a cached copy of the data element. Where replication is used and one of the devices holding a replica is unavailable, the system may use write off-loading.

主权项

1. A computer-implemented method of managing a distributed data storage system, the data storage system comprising a plurality of different devices and the method comprising:
storing location and availability information for a plurality of data elements stored on the devices, the location data of each data element being co-located with the associated data element and copies of the location data being co-located with the availability information for the plurality of data elements, availability information comprising at least one of battery level of a device or bandwidth of a network connection; receiving a request from a device for access to a data element; and, in response to receiving the request,
determining if the data element is available based on stored availability information, the determination based at least in part on a first cost function that accounts for the availability information; andif the data element is available, providing location information for the data element to the device.