Fast input/output in a content-addressable storage architecture with paged metadata

A system for minimizing read amplification for input/output (IO) where metadata is not in random access memory (RAM), comprising:

• a memory comprising computer-executable instructions;
• and
• a processor executing the computer-executable instructions, the computer-executable instructions when executed by the processor cause the processor to perform operations comprising:
• reading a first page and a corresponding second page from a storage device in a dual distributed layered architecture, the first page specifies a metadata page stored in persistent storage and having logical addresses of metadata, and the second page associates logical block addresses (LBAs) with corresponding physical locations for the metadata;
• reading data for a redundant array of independent disks (RAID) stripe according to an associated physical offset in the second page;
• accessing a stripe counter from the second page;
• comparing the stripe counter from the second page to a stripe counter held in memory;
• upon determining the stripe counter from the second page is the same as the first stripe counter held in memory:
• determining the data is valid;
• and
• reading the data according to associated physical offset in the second page and while bypassing a data module for the data;
• upon determining the stripe counter from the second page is not the same:
• accessing the data module, loading a third page, and reading a physical location of the data from the third page, the third page providing a hash value of the data and corresponding physical location of the data;
• accessing the physical location of the data during a read operation;
• and
• updating the second page.

A computer program product embodied on a non-transitory computer readable medium, the computer program product including instructions that, when executed by a computer causes the computer to perform operations comprising:

• reading a first page and a corresponding second page from a storage device in a dual distributed layered architecture, the first page specifies a metadata page stored in persistent storage and having logical addresses of metadata, and the second page associates logical block addresses (LBAs) with corresponding physical locations for the metadata;
• reading data for a redundant array of independent disks (RAID) stripe according to an associated physical offset in the second page;
• accessing a stripe counter from the second page;
• comparing the stripe counter from the second page to a stripe counter held in memory;
• upon determining the stripe counter from the second page is the same as the first stripe counter held in memory:
• determining the data is valid;
• and
• reading the data according to associated physical offset in the second page and while bypassing a data module for the data;
• upon determining the stripe counter from the second page is not the same:
• accessing the data module, loading a third page, and reading a physical location of the data from the third page, the third page providing a hash value of the data and corresponding physical location of the data;
• accessing the physical location of the data during a read operation;
• and
• updating the second page.