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High Performance Mirroring Method with Twin Tail Small Computer System Interface

IP.com Disclosure Number: IPCOM000115137D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Kunugi, M: AUTHOR

Abstract

The high performance mirroring with twin-tail Small Computer System Interface (SCSI) is described to gain the special improvement of system performance to intermittent peak transactions in a limited period of time. The system improves its performance to complete the write opration when the data are kept on the memory devices of the duplex system without physical write oprations to hard disk devices.

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High Performance Mirroring Method with Twin Tail Small Computer System
Interface

      The high performance mirroring with twin-tail Small Computer
System Interface (SCSI) is described to gain the special improvement
of system performance to intermittent peak transactions in a limited
period of time.  The system improves its performance to complete the
write opration when the data are kept on the memory devices of the
duplex system without physical write oprations to hard disk devices.

      Fig. 1 shows the example diagram of the duplex system and its
components.  The system unit #2 is operated as the slave and idle
machine.  System units are connected through the SCSI disk
controllers with the external SCSI cable.  The SCSI DISK CONTROLLER
has a auxiliary processor,memeory and etc.  with the BUS MASTER
capability that enables the system memory to be accessed directly.
The operating system has the paging mechanism.  Fig. 2 shows the
control and data flow of the High Performance Mirroring.  The request
with data initiated by the transaction program (1) are copied (2)
into the data buffer (3) by the controller logic (L1).  The
controller logic (L1) immediatetly transmits (4) them to the other
end of the shared SCSI bus and concurrently writes (5) them into the
non-pagiable write ahead log buffer (6) for any troubles with the
system unit #2.  The controller logic (L2) immediatetly returns (7)
the acknowledgment when the request and data are stored into its d...