Aliasing of exported paths in a storage system

• US 8,762,434 B1
• Filed: 10/08/2010
• Issued: 06/24/2014
• Est. Priority Date: 02/02/2004
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Haynes, Thomas D., Muhlestein, Mark, Noveck, David B.
• Primary Examiner(s): Perveen, Rehana
• Assistant Examiner(s): HAVAN, HUNG T
• Application Number:
  US12/901,276
• Time in Patent Office: 1,355 Days
• Field of Search: 707/821
• US Class Current: 707/827
• CPC Class Codes: G06F 16/13 File access structures, e.g. distributed indices arrangements of input from, or output to, record carriers G06F3/06
• CPC Class Codes: G06F 21/6218 to a system of files or objects, e.g. local or distributed file system or database
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

A storage system, such as a file server, uses pathname aliasing and exports a stored resource to clients by advertising to the clients a different pathname than the actual pathname of the resource.

Claims

1. A method comprising:

storing, by a storage system, a resource in the storage system according to a firstpathname;

configuring one or more entries of an exports table based upon one or more respective export rules for resources to be exported, wherein each of the entries of the exports table includes a filehandle of a resource, wherein each of the export rules includes an advertised path of a respective resource, and wherein said configuring comprises, for each of the one or more entries of the exports table,

selecting one of the one or more export rules,

when the selected export rule includes a directive identifying a physical path of the resource that is different than the advertised path of the selected export rule, storing, as the filehandle of the exports table entry, a filehandle retrieved using the physical path, and

when the export rule does not include the directive, storing, as the filehandle of the exports table entry, a filehandle retrieved using the advertised path;

receiving, by the storage system, a mount request from a client that specifies a secondpathname, wherein the second pathname is the advertised path of the resource and does not exist in physical storage of the storage system;

in response to the mount request, mapping, by the storage system, the second pathname to a filehandle using an entry of the exports table; and

returning the filehandle from the storage system to the client in response to the mount request, without the client having knowledge that the resource is stored according to the firstpathname, to enable the client to access the resource in the storage system with the filehandle.

2. A method as recited in claim 1, further comprising:

receiving a request to be granted access to the resource from the client, the request specifying the second pathname and not the first pathname; and

using the second pathname to identify the resource in response to the request.

3. A method as recited in claim 2, further comprising responding to the request by determining whether the client is permitted to access the resource.

4. A method as recited in claim 3, further comprising:

returning the filehandle of the resource in response to the request if the client which submitted the request is permitted to access the resource.

5. A method as recited in claim 4, wherein the entry of the exports table further includes access privileges for the resource.

7. A method as recited in claim 1, further comprising:

advertising the second pathname as the advertised pathname for the resource to a second client;

moving the resource to a new physical storage location represented by a third pathname without informing the second client;

receiving, by the storage system, a second mount request from the second client that specifies the second pathname;

in response to said receiving of the second mount request, mapping, by the storage system, the second pathname to a second filehandle using the entry of the exports table; and

returning the second filehandle from the storage system to the second client in response to the second mount request.

8. A method as recited in claim 1, further comprising:

storing, by the storage system, a second resource in the storage system according to a third pathname;

receiving, by the storage system, a second mount request from the client that specifies the third pathname, wherein the third pathname is the advertised path of the second resource;

in response to said receiving of the second mount request, mapping, by the storage system, the third pathname to a second filehandle using a second entry of the exports table; and

returning the second filehandle from the storage system to the client in response to the second mount request.

6. A storage server comprising:

a processor;

a storage interface through which to couple the storage server to a plurality of mass storage devices storing a plurality of exported resources; and

a memory having stored therein instructions which, when executed by the processor, cause the storage server to,

configure one or more entries of an exports table based upon one or more respective export rules for resources to be exported by performing a configuration process, wherein each of the entries of the exports table includes a filehandle of a resource, wherein each of the export rules includes an advertised path of a respective resource, wherein the configuration process includes, for each of the one or more entries,

selecting one of the one or more export rules,

when the selected export rule includes a directive identifying a physical path of the resource that is different than the advertised path of the selected export rule, storing, as the filehandle of the exports table entry, a filehandle retrieved using the physical path, and

when the export rule does not include the directive, storing, as the filehandle of the exports table entry, a filehandle retrieved using the advertised path; and

responsive to receiving mount requests that include advertised paths of the exported resources from one or more clients, return the filehandles of entries of the exports table identified using the advertised paths, wherein at least some of the advertised paths of the received mount requests are not the same as the physical paths of the respective exported resources.

9. A storage server as recited in claim 6, wherein the instructions further cause the

storage server to:

responsive to receiving access requests for the exported resources from one or more clients that include the returned filehandles, identify the entries of the exports table using the returned filehandles; and

determine whether the respective one or more clients have permission to make the access requests for the exported resources based upon the identified entries.

10. A storage server as recited in claim 6, wherein the instructions further cause the

storage server to:

prior to the receiving of the mount requests, move one or more of the exported resources to new physical storage locations according to new physical paths without informing the one or more clients.

11. A method, comprising:

configuring an entry of an exports table based upon an export rule for a resource to be exported from a storage system, wherein the entry of the exports table includes a filehandle of the resource, wherein the export rule includes an advertised path of the resource, and wherein said configuring comprises,

selecting the export rule,

when the selected export rule includes a directive identifying a physical path of the resource that is different than the advertised path of the selected export rule, storing, as the filehandle of the entry of the exports table, a filehandle retrieved using the physical path, and

when the export rule does not include the directive, storing, as the filehandle of the entry of the exports table, a filehandle retrieved using the advertised path;

advertising, by the storage system to a client, an export point for the resource stored by the storage system, wherein the client is not aware that the advertised path is not the physical path of the resource;

receiving, by the storage system from the client, a mount request for the resource that includes the advertised path;

responsive to the receipt of the mount request, using the advertised path to identify the entry in the exports table including the filehandle for the resource; and

returning, by the storage system, the filehandle to the client.

12. A method as recited in claim 11, further comprising:

moving the resource to a new physical location in the storage system according to a different path without notifying the client of the moving, wherein the filehandle for the resource is updated to map to the new physical location in the storage system;

receiving, from the client, a different mount request for the resource that includes the advertised path;

responsive to the receipt of the different mount request, using the advertised path to identify the entry in the exports table including the filehandle for the resource; and

returning, by the storage system, the filehandle to the client.

13. A storage server comprising:

a processor;

a storage interface through which to couple the storage server to a plurality of mass storage devices storing a plurality of exported resources; and

a memory having stored therein instructions which, when executed by the processor, cause the storage server to,

configure an entry of an exports table based upon an export rule for a resource to be exported, wherein the entry of the exports table includes a filehandle of the resource, wherein the export rule includes an advertised path of the resource, and wherein said configure comprises,

select the export rule,

when the selected export rule includes a directive identifying a physical path of the resource that is different than the advertised path of the selected export rule, store, as the filehandle of the entry of the exports table, a filehandle retrieved using the physical path, and

when the export rule does not include the directive, store, as the filehandle of the entry of the exports table, a filehandle retrieved using the advertised path;

advertise, to a client, an export point for the resource, wherein the client is not aware that the advertised path is not the actual physical path of the resource,

responsive to the receipt, from the client, of a mount request for the resource that includes the advertised path, use the advertised path to identify the entry in the exports table including the filehandle for the resource, and

return the filehandle to the client.

14. A storage server as recited in claim 13, wherein the instructions further cause the storage server to:

move the resource to a new physical location according to a different path without notifying the client of the move, wherein the filehandle for the resource is updated to map to the new physical location in the storage system;

responsive to a receipt, from the client, of a different mount request for the resource that includes the advertised path, use the advertised path to identify the entry in the exports table including the filehandle for the resource; and

return the filehandle to the client.