Storing lossy hashes of file names and parent handles rather than full names using a compact table for network-attached-storage (NAS)
Multiple Network Attached Storage (NAS) appliances are pooled together by a virtual NAS translator, forming one common name space visible to clients. Clients send messages to the virtual NAS translator with a file name and a virtual handle of the parent directory that are concatenated to a full file-path name and compressed by a cryptographic hash function to generate a hashed-name key. The hashed-name key is matched to a storage key in a table. The full file-path name is not stored, reducing the table size. A unique entry number is returned to the client as the virtual file handle that is also stored in another table with one or more native file handles, allowing virtual handles to be translated to native handles that the NAS appliance servers use to retrieve files. File movement among NAS servers alters native file handles but not virtual handles, hiding NAS details from clients.
1. An apparatus, comprising:
a network interface configured to receive a file-access request from a client over a network, wherein the file-access request includes a virtual file handle having a unique identifier;
a translator coupled to the network interface, and configured to receive from the network interface the virtual file handle, extract the unique identifier, and determine a native file handle from an entry in a translation table corresponding to the unique identifier, wherein the entry in the translation table is selected from one of a plurality of entries in the translation table and wherein each of the plurality of entries in the translation table includes a server name of a server that stores a file and information related to at least one of read-write privileges, creation, or modification of the file;
a request forwarder coupled to the translator and the network interface, and configured to generate a translated file-access request that includes the native file handle; and
a storage device configured to store the file of the file-access request and to receive the translated file-access request from the request forwarder.
2. The apparatus of claim 1 , wherein the storage device is a network attached (NAS) appliance server selected from a plurality of NAS appliance servers.
3. The apparatus of claim 1 , wherein the translation table is an open-file translation table that stores entries for currently open files.
4. The apparatus of claim 1 , further comprising:
a hash engine coupled to the network interface, and configured to receive from the network interface, a file name and path location included in an initial file-access request from the client, and to generate a hashed-name key based at least in part on the file name and the path location.
5. The apparatus of claim 4 , further comprising a reply generator coupled to the network interface, and configured to generate, in response to the initial file-access request, a reply including the virtual file handle to be sent through the network interface to the client.
6. The apparatus of claim 1 , wherein the apparatus is configured to move the file to a second storage device by changing entries in the translation table and by sending commands to the storage device and the second storage device to physically move the file to the second storage device.