Browse Prior Art Database

Sequential Data Transfer Handling Method

IP.com Disclosure Number: IPCOM000013299D
Original Publication Date: 1999-Dec-01
Included in the Prior Art Database: 2003-Jun-18
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Kazunori Inoue: AUTHOR [+3]

Abstract

*Title of disclosure (in English)

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 70% of the total text.

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Sequential Data Transfer Handling Method

*Title of disclosure (in English)

Sequential Data Transfer Handling Method

*Idea of disclosure

Disclosed is a algorithm to control effective data transfer for HDD (Hard Disk Drive)
sequential READ/WRITE operation.

When a command is received from a host, HDD have to check if the requested data can be
send from/to the buffer by searching all the data buffer. If this checking is done with
the SCSI bus being connected, the bus utilization is getting low because this checking
may not be negligible. Or this checking is done after disconnection, there requires
disconnection and reconnection hand-shaking overhead and these are also negligible.

This algorithm can detect if it is sequential or not without searching data buffer.
And if it is sequential detected, the data transfer can be started immediately.

So, the SCSI bus utilization gets high and it can get much system performance.

~~~Hard Disk Controller records the last command information
~~~- Initiator ID
~~~- READ or WRITE command

- Last LBA of the command
- Data transfer is completed or not

~~~Hard Disk Controller checks the newly received command if data transfer can be
started or not referring the information recorded at 1.

- Same Initiator
- Same Command (READ or WRITE)
- The starting lba is sequential to the last lba of the previous one
- The previous command completes the data transfer

~~~If all the condition are met, Starts the data transfer to/from the same buffer
sequentially. If...