Methods and structure for SCSI/IDE translation in a storage subsystem

• US 6,934,769 B2
• Filed: 07/29/2002
• Issued: 08/23/2005
• Est. Priority Date: 07/29/2002
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Smith, Gerald Edward
• Primary Examiner(s): Gaffin, Jeffrey
• Assistant Examiner(s): Chen, Alan S
• Application Number:
  US10/207,672
• Publication Number:
  US 20040019706A1
• Time in Patent Office: 1,121 Days
• Field of Search: 710/5, 710/11, 710/32, 710/8, 711/114
• US Class Current: 710/5
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0661 Format or protocol conversion arrangements
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

Methods and associated structure operable within a SCSI-based storage subsystem to adapt the storage controller for use with non-SCSI disk drives. A firmware layer of the present invention intercepts SCSI read/write requests and pass through command blocks (CDBs) generated by the storage management core of the controller and translates the requests and command structures into corresponding command structures for transmission to a non-SCSI disk drive. In like manner, the firmware layer of the present invention receives status information from non-SCSI disk drives and translates the status information into corresponding SCSI compatible status information. In one exemplary preferred embodiment, a storage subsystem designed for interaction with SCSI disk drives may be adapted in accordance with the present invention to utilize lower-cost, commodity disk drives such as IDE compatible disk drives.

Claims

1. A storage subsystem comprising:

a storage controller adapted for controlling SCSI storage devices using SCSI command and status information exchanges and adapted for coupling to a host system for receiving host I/O requests wherein said command and status information exchanges include one or more SCSI command descriptor blocks generated by said storage controller;

a non-SCSI storage device adapted to process non-SCSI command and status information exchanges; and

a conversion element coupling said storage controller to said storage device for converting between SCSI command and status information exchanged used by said storage controller and non-SCSI command and for converting status information exchanges used by said non-SCSI storage device,

wherein the conversion element is adapted to generate multiple non-SCSI commands in response to receipt of a SCSI command exchange from said storage controller.

2. The subsystem of claim 1 wherein said conversion element includes:

a pass-through SCSI CDB conversion element to convert pass-through SCSI commands for application to said non-SCSI storage device.

3. The subsystem of claim 1 wherein said conversion element includes:

a read/write SCSI message conversion element to convert read and write SCSI requests for application to said non-SCSI storage device.

4. The subsystem of claim 1 wherein said conversion element includes:

a status conversion element for receiving status information from said non-SCSI storage device and converting said status information to related SCSI status information.

5. The subsystem of claim 1 wherein said non-SCSI a storage device is an IDE compliant storage device.

6. The subsystem of claim 1 wherein said storage controller is a RAID storage controller.

7. A storage controller comprising:

a SCSI-based RAID storage control core element;

an IDE interface for coupling said storage controller to a plurality of IDE disk drives;

a SCSI/IDE command conversion element for converting commands generated by said SCSI-based RAID storage controller core element for application to an IDE disk drive coupled to said IDE interface wherein said commands include one or more SCSI command descriptor blocks generated by said core element; and

an IDE/SCSI status conversion element for converting status information received from an IDE disk drive coupled to said IDE interface for application to said SCSI-based RAID storage control core element,

wherein the command conversion element is adapted to generate multiple commands for application to the IDE disk drive in response to receipt of a SCSI command from said RAID storage controller.

8. A system comprising:

a plurality of non-SCSI storage devices; and

a SCSI-based storage controller communicatively coupled to said plurality of non-SCSI storage devices wherein said SCSI-based storage controller includes;

storage management core means for managing storage of data on said plurality of non-SCSI storage devices; and

SCSI command conversion means for converting SCSI commands generated by said storage management core means for application to said plurality of non-SCSI storage devices wherein said SCSI commands include one or more SCSI command descriptor blocks generated by said SCSI-based storage controller,

wherein the conversion means further comprises;

command mapping means for mapping each SCSI command to a corresponding sequence of one or more IDE commands,

wherein the conversion means is adapted to generate multiple IDE commands in response to receipt of a SCSI command from said storage controller.

9. The system of claim 8 wherein said controller further comprises:

SCSI status conversion means for receiving status information from said plurality of non-SCSI storage devices and for converting said status information to equivalent SCSI status information and for applying said equivalent SCSI status to said storage management core means.

10. The system of claim 9 wherein said plurality of non-SCSI storage devices comprises a plurality of IDE disk drives and wherein said SCSI status conversion means comprises:

means for receiving IDE status information from said plurality of IDE disk drives; and

status mapping means for mapping said IDE status information to a corresponding sequence of one or more SCSI status messages.

11. A method operable within a storage controller comprising the steps of:

generating SCSI commands to manipulate data stored on disk drive associated with said storage controller wherein said SCSI commands include one or more SCSI command descriptor blocks generated by said storage controller;

converting said SCSI commands to non-SCSI commands wherein the conversion includes converting a SCSI command into multiple non-SCSI command; and

providing a mapping table wherein entries of the table maps a corresponding SCSI command to a conversion function for generating said non-SCSI commands,

wherein the step of converting said SCSI commands comprises;

looking up said SCSI command in said mapping table to identify the corresponding conversion function; and

invoking said corresponding conversion function to generate said non-SCSI commands.

12. The method of claim 11 further comprising the steps of:

receiving non-SCSI status information from said non-SCSI disk drives;

converting said non-SCSI status information to SCSI status information; and

applying said SCSI status information to storage management elements operable within said storage controller.