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

• US 20040019706A1
• Filed: 07/29/2002
• Published: 01/29/2004
• 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
• Granted Patent: US 6,934,769 B2
• Time in Patent Office: Days
• US Class Current: 710/1
• 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;

a non-SCSI storage device; and

a conversion element coupling said storage controller to said storage device for converting information exchanged between said storage controller and said non-SCSI storage device.

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 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; 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.

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 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.

9. The system of claim 8 wherein said plurality of non-SCSI storage devices comprises a plurality of IDE disk drives and wherein said SCSI command conversion means comprises:

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

10. 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.

11. The system of claim 10 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.

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

generating SCSI commands to manipulate data stored on disk drives associated with said storage controller;

converting said SCSI commands to non-SCSI commands; and

applying said non-SCSI commands to non-SCSI disk drives coupled to said storage controller.

13. The method of claim 12 further comprising the step of:

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.

14. The method of claim 12 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.