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Common RAID Disk Data Format

Specification

Version 2.0 Revision 19

This document has been released and approved by the SNIA. The SNIA believes that the ideas, methodologies and technologies described in this document accurately represent the SNIA goals and are appropriate for widespread distribution. Suggestion for revision should be directed to http://www.snia.org/feedback/.

SNIA Technical Position

March 27, 2009

Common RAID Disk Data Format (DDF) SNIA Technical Position 2 Version 2.0 rev 19

Revision History

Revision Date Sections Originator: Comments 1.2 7/28/2006 Arnold Jones Officially published as SNIA

Technical Position. 1.20.01 8/16/2006 Bill Dawkins Development draft of the

next version of the DDF Specification

1.20.02 2/22/2007 Bill Dawkins Added content to support large block size drives

1.20.03 03/02/2007 Ramamurthy Krithivas

Added RAID 5 Rotate after N Stripes equations, and RAID 6 PQ ordered equation.

1.20.04 3/6/2007 Bill Dawkins Modified content to support large block size drives.

1.20.05 5/3/2007 Various Bill Dawkins Updated draft to include all 1.2 errata. Added variable entries to BBM_Log section. Added enhanced definition of VD states to account for MDF RAID. Added path information for SATA drives in PDE structures.

1.20.06 06/21/2007 Various Ramamurthy Krithivas

First Draft of the MDF RAID Algorithm.

1.20.07 07/30/2007 4.2.25 Ramamurthy Krithivas

Updated 4.2.25 based on TWG review of 06/26/2007.

1.20.11 11/21/2007 Bill Dawkins Draft for IP review Version 2.0

rev 17 10/8/2008 Various Bill Dawkins Draft candidate for

Technical Council submission.

Version 2.0 rev 18

11/18/2008 Various Bill Dawkins Updated draft candidate for Technical Council submission.

Version 2.0 rev 19

11/21/2008 Various Bill Dawkins Approved draft submitted to Technical Council

Suggestion for changes or modifications to this document should be submitted at http://www.snia.org/feedback/.

Common RAID Disk Data Format (DDF) SNIA Technical Position 3 Version 2.0 rev 19

Typographical Conventions

The key words MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL in this document are to be interpreted as described in RFC2119 [http://www.ietf.org/rfc/rfc2119.txt].

Usage

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Copyright 2005 2008, Storage Networking Industry Association.

Common RAID Disk Data Format (DDF) SNIA Technical Position 4 Version 2.0 rev 19

TABLE OF CONTENTS

1 INTRODUCTION ....................................................................................................... 8

2 OVERVIEW ............................................................................................................... 92.1 Purpose ................................................................................................................. 92.2 Design Considerations ...................................................................................... 10

2.2.1 Location ....................................................................................................... 102.2.2 Locality ........................................................................................................ 102.2.3 DDF Structure Size ..................................................................................... 102.2.4 DDF Structure Contents .............................................................................. 102.2.5 DDF Structure Redundancy ........................................................................ 11

3 DEFINITIONS.......................................................................................................... 123.1 RAID Terms ......................................................................................................... 12

3.1.1 Virtual Disk (VD) .......................................................................................... 123.1.2 Basic Virtual Disk (BVD) .............................................................................. 123.1.3 Secondary Virtual Disk (SVD) ..................................................................... 123.1.4 Disk Grouping .............................................................................................. 123.1.5 Foreign configuration ................................................................................... 123.1.6 Legacy or Pass-through Disk ...................................................................... 12

4 RAID LEVELS AND RAID LEVEL QUALIFIERS ................................................... 134.1 Primary RAID Level ............................................................................................ 134.2 RAID Level Qualifier ........................................................................................... 13

4.2.1 RAID-0 Simple Striping (PRL=00, RLQ=00) ................................................ 164.2.2 RAID-1 Simple Mirroring (PRL=01, RLQ=00) .............................................. 184.2.3 RAID-1 Multi Mirroring (PRL=01, RLQ=01) ................................................. 194.2.4 RAID-3 Non-Rotating Parity 0 (PRL=03, RLQ=00) ...................................... 204.2.5 RAID-3 Non-Rotating Parity N (PRL=03, RLQ=01) ..................................... 224.2.6 RAID-4 Non-Rotating Parity 0 (PRL=04, RLQ=00) ...................................... 244.2.7 RAID-4 Non-Rotating Parity N (PRL=04, RLQ=01) ..................................... 264.2.8 RAID-5 Rotating Parity 0 with Data Restart (PRL=05, RLQ=00) ................. 284.2.9 RAID-5 Rotating Parity N with Data Restart (PRL=05, RLQ=02) ................ 314.2.10 RAID-5 Rotating Parity N with Data Continuation (PRL=05, RLQ=03) ..... 334.2.11 RAID-5E Rotating Parity 0 with Data Restart (PRL=15, RLQ=00) ............ 354.2.12 RAID-5E Rotating Parity N with Data Restart (PRL=15, RLQ=02) ........... 384.2.13 RAID-5E Rotating Parity N with Data Continuation (PRL=15, RLQ=03) .. 404.2.14 RAID-5EE Rotating Parity 0 with Data Restart (PRL=25, RLQ=00) ......... 424.2.15 RAID-5EE Rotating Parity N with Data Restart (PRL=25, RLQ=02) ......... 454.2.16 RAID-5EE Rotating Parity N with Data Continuation (PRL=25, RLQ=03) 484.2.17 RAID-5R Rotating Parity 0 after R Stripes with Data Restart (PRL=35, RLQ=00) 504.2.18 RAID-5R Rotating Parity N after R Stripes with Data Restart (PRL=35, RLQ=02) 53

Common RAID Disk Data Format (DDF) SNIA Technical Position 5 Version 2.0 rev 19

4.2.19 RAID-5R Rotating Parity N after R Stripes with Data Continuation (PRL=35, RLQ=03) ................................................................................................. 554.2.20 RAID-1E Integrated Adjacent Stripe Mirroring (PRL= 11, RLQ=00) ......... 574.2.21 RAID-1E Integrated Offset Stripe Mirroring (PRL=11, RLQ=01) .............. 594.2.22 RAID-6 Rotating Parity 0 with Data Restart (PRL=06, RLQ=01) .............. 61

4.2.22.1 Parity Re-computation on Block Update ....................................................................................... 644.2.22.2 Galois Field Operations ................................................................................................................ 64

4.2.23 RAID-6 Rotating Parity N with Data Restart (PRL=06, RLQ=02) ............. 684.2.23.1 Parity Re-computation on Block Update ....................................................................................... 704.2.23.2 Galois Field Operations ................................................................................................................ 70

4.2.24 RAID 6 Rotating Parity N with Data Continuation (PRL=06, RLQ=03) ..... 714.2.24.1 Parity Re-computation on Block Update ....................................................................................... 734.2.24.2 Galois Field Operations ................................................................................................................ 73

4.2.25 Multi Disk Failure RAID Rotating Parity 0 with Data Restart (PRL=07, RLQ=00) 74

4.2.25.1 Galois Field Generation ................................................................................................................ 764.2.25.2 Constant Matrix Generation .......................................................................................................... 774.2.25.3 Galois Parity Computation ............................................................................................................ 79

4.2.26 Multi Disk Failu

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