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Browse Prior Art Database

Effective Utilization of Write Data

IP.com Disclosure Number: IPCOM000117050D
Original Publication Date: 1995-Dec-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Kanamaru, A: AUTHOR [+3]

Abstract

Disclosed is a control algorithm of multiple segmented cache memory on Hard Disk Drive (HDD). Write data which is transferred from the controller is effectively preserved in the cache memory even after the execution of the write. The preserved data is utilized as read cache data for the consequent accesses from the controller.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 76% of the total text.

Effective Utilization of Write Data

      Disclosed is a control algorithm of multiple segmented cache
memory on Hard Disk Drive (HDD).  Write data which is transferred
from the controller is effectively preserved in the cache memory even
after the execution of the write.  The preserved data is utilized as
read cache data for the consequent accesses from the controller.

      On a write data transfer the block address which is transferred
from the controller is compared with the data which has already
stored in the cache memory.  If some segmented memories store
correspond address with the transferred data, a segmented memory
which stores the most corresponded blocks is used on the transfer.
Additionally, the same pages in the memory are used on the transfer.
For example, the following describes a case that two segmented
memories exist.  Fig. 1 shows the original contents of those memories
before write.  Memory-1 stores 10 blocks' data from address 10 to 19
and Memory-2 does 10 data from 15 to 24.  Now if write command from
address 12 to 16 is issued, the contents of two memories are
verified.  Memory-1 is storing all 5 blocks from address 12 to 16 and
Memory-2 is doing only 2 blocks; 15 and 16.  Then Memory-1 is
selected for the data transfer.  Now the data from address 12 to 16
are stored in pages 2 to 6 as described in Fig. 1.  Therefore, pages
2 to 6 are used for the data transfer.  Additionally pages 0 and 1 in
Memory-2 have to be flushed from the c...