US 9,176,887 B2Granted

Compressed level two block buffer metadata cache

OwnerJoseph Richard Habermanninventor

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Abstract

Example apparatus and methods provide metadata for a file system operation from a multi-level data store. The data store may include an in-memory level one (L1) cache, an in-memory level two (L2) cache, and an external metadata store not located in the memory associated with the L1 and L2 caches. The L1 cache stores metadata in a non-compressed format that can directly service a file system operation while the L2 cache stores metadata in a compressed format that cannot directly service an operation. Metadata to support a file system operation may be sought in the L1 cache first, then in the L2 cache, and then finally in the external metadata store. When metadata is provided from the L2 cache, it is decompressed before being provided to the L1 cache. Metadata added to the L2 cache may be compressed after or in parallel with being provided to the L1 cache.

Claims18

Dependent claims

A non-transitory computer-readable medium storing computer-executable instructions that when executed by a computer cause the computer to perform a method, the method comprising:

providing metadata for a file system operation from a three level data store,
the three level data store comprising:
a level one metadata cache stored in a memory;
a level two metadata cache stored in the memory;
and
a metadata store not stored in the memory,
where the level one metadata cache stores metadata in a non-compressed format that can directly service the file system operation,
where the level two metadata cache stores metadata in a compressed format that cannot directly service the file system operation, and
where providing metadata for the file system operation includes:
upon determining that metadata is located in the level one metadata cache, providing metadata to the file system from the level one metadata cache, and
upon determining that metadata is not located in the level one cache;
upon determining that metadata is located in the level two metadata cache,
decompressing metadata,
providing metadata to the level one metadata cache, and
providing metadata to the file system,
and
upon determining that metadata is not located in the level two metadata cache,
retrieving metadata from the metadata store,
providing metadata to the level one metadata cache, and
providing metadata to the file system.

17 more elements

An apparatus, comprising:

a processor;
a memory configured to store metadata for a file system;
a set of logics;
and
an interface that connects the processor, the memory, and the set of logics;
the set of logics being configured to provide metadata for an operation performed by the file system, the set of logics comprising:
a first logic configured to manage a first cache, where the first cache is located in the memory, and where metadata stored in the first cache is not compressed;
a second logic configured to manage a second cache, where the second cache is located in the memory, and where metadata stored in the second cache is compressed, and
a third logic configured to provide metadata for the operation, where the third logic is configured:
to provide metadata for the operation from the first cache when metadata is available from the first cache,
to provide metadata from the second cache when metadata is available from the second cache but not from the first cache, and
to provide metadata from an external source when metadata is not available in the second cache and is not available in the first cache.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/147,564Filed 5 Jan 2014
Published: US 2015/0193353 A19 Jul 2015
Granted: 3 Nov 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G06F 12/0897
Caches characterised by their organisation or structure: with two or more cache hierarchy levels
G06F 12/0802
In hierarchically structured memory systems, e.g. virtual memory systems: addressing of a memory level in which the access to the desired data or…
G06F 12/0811
Multiuser, multiprocessor or multiprocessing cache systems: with multilevel cache hierarchies
G06F 12/0848
Cache with multiple tag or data arrays being simultaneously accessible: partitioned cache, e.g. separate instruction and operand caches