Reading from a site cache in a distributed file system

• US 10,445,296 B1
• Filed: 09/24/2015
• Issued: 10/15/2019
• Est. Priority Date: 12/05/2014
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Inventors: Panghal, Vijay
• Primary Examiner(s): Bataille, Pierre Miche
• Application Number:
  US14/864,399
• Time in Patent Office: 1,482 Days
• Field of Search: 711118, 711119, 711120
• CPC Class Codes: G06F 16/148 File search processing
• CPC Class Codes: G06F 16/172 Caching, prefetching or hoarding of files
• CPC Class Codes: G06F 16/182 Distributed file systems
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching

Abstract

A method, article of manufacture, and apparatus for providing a site cache in a distributed file system is discussed. Data objects may be read from a site cache rather than an authoritative object store. This provides performance benefits when a client reading the data has a better connection to the site cache than to the authoritative object store.

Claims

1. A method comprising:

performing the following operations at a site cache that includes stored data objects;

receiving a read request from a client, wherein the read request includes a data object identifier of a data object and a location reference for an authoritative object store, the location reference being received from a metadata server by way of the client;

when it is determined from the data object identifier that the data object is stored at the site cache, returning the data object from the site cache to the client; and

performing the following operations when it is determined that the data object is not stored at the site cache;

forwarding the read request, received from the client, from the site cache to the authoritative object store at the location reference;

receiving, at the site cache, the data object from the authoritative object store in response to the forwarded read request;

storing the data object in a transient object store of the site cache;

updating a metadata store included as part of the site cache to include the data object identifier; and

returning the data object to the client.

2. The method of claim 1, wherein determining that the data object is stored at the site cache comprises querying a metadata store included as part of the site cache.

3. The method of claim 2, wherein the metadata store is queried from a traffic processing engine of the site cache.

4. The method of claim 2, wherein the metadata store is queried from a transient object store service of the site cache.

5. A system comprising a non-transitory computer readable storage medium and a processor configured to execute instructions which, when executed by the processor, perform operations comprising:

receiving a read request from a client, wherein the read request includes a data object identifier of a data object and a location reference for an authoritative object store, the location reference being received from a metadata server by way of the client;

when it is determined from the data object identifier that the data object is stored at the site cache, returning the data object from the site cache to the client; and

performing the following operations when it is determined that the data object is not stored at the site cache;

forwarding the read request, received from the client, from the site cache to the authoritative object store at the location reference;

receiving, at the site cache, the data object from the authoritative object store in response to the forwarded read request;

storing the data object in a transient object store of the site cache;

updating a metadata store included as part of the site cache to include the data object identifier; and

returning the data object to the client.

6. The system of claim 5, wherein determining that the data object is stored at the site cache comprises querying a metadata store associated with the site cache.

7. The system of claim 6, wherein the metadata store is queried from a traffic processing engine of the site cache.

8. The system of claim 6, wherein the metadata store is queried from a transient object store service of the site cache.

9. A non-transitory computer readable storage medium comprising instructions which, when executed by a processor, perform operations comprising:

receiving a read request from a client, wherein the read request includes a data object identifier of a data object and a location reference for an authoritative object store, the location reference being received from a metadata server by way of the client;

when it is determined from the data object identifier that the data object is stored at the site cache, returning the data object from the site cache to the client; and

performing the following operations when it is determined that the data object is not stored at the site cache;

forwarding the read request, received from the client, from the site cache to the authoritative object store at the location reference;

receiving, at the site cache, the data object from the authoritative object store in response to the forwarded read request;

storing the data object in a transient object store of the site cache;

updating a metadata store included as part of the site cache to include the data object identifier; and

returning the data object to the client.

10. The non-transitory computer readable storage medium of claim 9, wherein determining that the data object is stored at the site cache comprises querying a metadata store associated with the site cache.

11. The non-transitory computer readable storage medium of claim 10, wherein the metadata store is queried from a traffic processing engine of the site cache.

12. The non-transitory computer readable storage medium of claim 10, wherein the metadata store is queried from a transient object store service of the site cache.

13. The non-transitory computer readable storage medium of claim 9, wherein the location reference received from the metadata server comprises a uniform resource locator.