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Modifying the SCSI / Fibre Channel Block Size. Presented by Keith Bonneau, John Chrzanowski and Craig O’Brien Advised by Robert Kinicki and Mark Claypool. Project Goals. Edit the Fibre Channel frame to utilize 100% of the payload for data transfer.

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Modifying the scsi fibre channel block size

Modifying the SCSI / Fibre Channel Block Size

Presented by Keith Bonneau,

John Chrzanowski and Craig O’Brien

Advised by Robert Kinicki and Mark Claypool


Project goals
Project Goals

  • Edit the Fibre Channel frame to utilize 100% of the payload for data transfer.

  • Change the block size of the hard disk to reflect the changes to the frame.

  • Make these changes transparent to the user and the Linux kernel.

  • Why?


Storage area network san
Storage Area Network (SAN)

  • Improved reliability.

    • Better data access and backup.

  • Flexible Architecture.

    • Load balancing.

    • Supports many different protocols.

  • Superior to direct attached storage.


San overview
SAN Overview

The specific configuration of the SAN we used for the project.


Fibre channel
Fibre Channel

  • Long cable length up to 10 km.

  • Transfer speeds up to 2 gbps.

  • Layered interface.

  • Data must be sent through frames.

  • Used as a backbone for most commercial networks.


Small computer system interface scsi
Small Computer System Interface (SCSI)

  • Communicates through specific commands.

  • Limited by cable length, and number of devices.

    • 25 meter maximum cable length.

    • 15 devices allowed on the SCSI bus.

  • Interfaces well with Fibre Channel.


Methodology
Methodology

  • Located and modified the driver that detects the SCSI devices.

  • Compiled the kernel to reflect these changes.

    • Required a reconfiguration of the Linux kernel and a new image.


Methodology1
Methodology

  • Performed a low level format on the hard disk to increase its block size from 512 bytes to 528 bytes.

  • Modified the host bus adapter driver in order to handle the extra 16 bytes being transmitted.


Results
Results

Figure 1: Writing to the 512 byte disk

Figure 2: Writing to the 528 byte disk


Conclusion
Conclusion

  • The hard disk needs a firmware update from Seagate.

  • Upon completion, the resulting data transfer would be more secure.

  • Relatively no added time or size, making this ideal for streaming media.


Future recommendations
Future Recommendations

  • Read the host bus adapter code and search for alternative modification points.

  • Add and remove the 16 bytes completely on the SCSI layer.

  • Request access to appropriate Windows source files to adapt their platform.



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