Systems and methods for raid acceleration

Patent metadata

Field	Value
Publication number	US-9268644-B1
Application number	US-201213449628-A
Country	US
Kind code	B1
Filing date	Apr 18, 2012
Priority date	Apr 18, 2011
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

Abstract

A RAID module for a RAID controller that includes a thin RAID layer and a thin disk layer. The thin RAID layer sits between an operating system layer and a RAID stack, and intercepts and fields requests and I/Os made the between operating system and the RAID stack. The thin disk layer sits between the RAID stack and the disks that comprise the array, and intercepts and fields requests and I/Os made between the RAID stack and the array. The module may maintain a bitmap with an entry corresponding to each stripe of the array. When the module detects that a stripe has zero data, the entry in the bitmap for the stripe is set to 0. When the module detects that data has been written to a stripe, the entry in the bitmap for the stripe is set to 1.

First claim

What is claimed:

1. A method comprising:
intercepting, by a thin disk layer located between a RAID stack and a RAID array, a read I/O that was sent from the RAID stack directed to the RAID array, wherein the RAID array comprises a plurality of stripes which are managed by the RAID stack;
determining, by the thin disk layer, a stripe associated with the I/O;
retrieving, by the thin disk layer, a bitmap associated with the RAID array, wherein the bitmap comprises an entry associated with each of the plurality of stripes and each entry has a corresponding value;
determining, by the thin disk layer, that the corresponding value associated with the determined stripe in the bitmap indicates that the strip contains invalid data;
without providing the I/O to the RAID array, discarding, by the thin disk layer, the I/O and providing, by the thin disk layer, zero data to the RAID stack as a response to the sent I/O; and
providing, by a thin RAID layer located between the RAID stack and an operating system or application layer, an error message to the operating system or application layer indicating that the stripe contains invalid data.

2. The method of claim 1 , wherein the I/O is an initialization related I/O and further comprising sending, by the thin disk layer, a message to the RAID stack purporting that the discarded I/O was received and completed by the RAID array.

3. A data storage system, comprising:
a storage server;
a physical storage device associated with storage server;
a processing unit associated with the storage server; and
one or more modules for execution on the processing unit operable to:
intercept, by a thin disk layer located between a RAID stack and a RAID array, a read I/O that was sent from the RAID stack directed to the RAID array, wherein the RAID array comprises a plurality of stripes which are managed by the RAID stack;
determine, by the thin disk layer, a stripe associated with the I/O;
retrieve, by the thin disk layer, a bitmap associated with the RAID array, wherein the bitmap comprises an entry associated with each of the plurality of stripes and each entry has a correspond value;
determine, by the thin disk layer, that the corresponding value associated with the determined stripe in the bitmap contains invalid data;
without providing the I/O to the RAID array, to discard, by the thin disk layer, the I/O and to provide, by the thin disk layer, zero data to the RAID stack as a response to the sent I/O; and
provide, by a thin RAID layer located between the RAID stack and an operating system or application layer, an error message to an operating system or application layer indicating that the stripe contains invalid data.

4. The data storage system of claim 3 , wherein the I/O is an initialization related I/O, and wherein the one or more modules for execution on the processing unit are further operable to send, by the thin disk layer, a message to the RAID stack purporting that the discarded I/O was received and completed by the RAID array.

Assignees

• Subramanian Srikumar
• Gopalakrishnan Sankarji
• Ganapathy Narayanaswami
• Chatterjee Paresh
• Chatterjee Udita
• American Megatrends Inc

Inventors

• Subramanian Srikumar
• Gopalakrishnan Sankarji
• Ganapathy Narayanaswami
• Chatterjee Paresh

Classifications

• G06F11/1076 Primary

  Parity data used in redundant arrays of independent storages, e.g. in RAID systems · CPC title

• G06F2211/1057

  Parity-multiple bits-RAID6, i.e. RAID 6 implementations · CPC title

• G06F2211/1004

  Adaptive RAID, i.e. RAID system adapts to changing circumstances, e.g. RAID1 becomes RAID5 as disks fill up · CPC title

• G06F2211/1007

  Addressing errors, i.e. silent errors in RAID, e.g. sector slipping and addressing errors · CPC title

• G06F11/1435 Primary

  using file system or storage system metadata · CPC title