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Integrated Disk Management to Provide High Performance Logical Drives for Multiple Accesses and Large Sequential Accesses to a Multi-Disk Storage Subsystem

IP.com Disclosure Number: IPCOM000104975D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 108K

Publishing Venue

IBM

Related People

Hu, L: AUTHOR

Abstract

Disclosed is a logical drive management system which provides two additional types of logical drives across multiple disks to improve I/O performance for two types of disk I/O requests: multiple random and large sequential accesses. A hot spot detection and shuffling scheme is used to maintain the performance of the random type of logical drives.

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Integrated Disk Management to Provide High Performance Logical Drives for Multiple Accesses and Large Sequential Accesses to a Multi-Disk Storage Subsystem

      Disclosed is a logical drive management system which provides
two additional types of logical drives across multiple disks to
improve I/O performance for two types of disk I/O requests:  multiple
random and large sequential accesses.  A hot spot detection and
shuffling scheme is used to maintain the performance of the random
type of logical drives.

      Multitasking operating systems like OS/2*, together with small
and inexpensive SCSI (Small Computer System Interface) disks,
dramatically change the personal computing environment.  For example,
a new strategy in OS/2 2.0* disk device driver enables the device
driver to dispatch to a SCSI host adapter a list of device commands.
Then the SCSI host adapter can issue disk I/O commands to several
disks at the same time.

      However, traditional disk management has not taken advantage of
the new storage subsystem environment.  Traditional disk management
partitions available space on a disk device into several logical
drives, as shown in Figure 1.  Each logical drive is treated by the
file system as a single device.  Most applications do not know or
utilize logical drives beyond the one they reside.  Therefore, the
majority of the disk I/O requests from the application are issued to
a single disk.

      The proposed solution is an integrated disk management system
that breaks down the boundaries between disks.  Instead of only one
type of logical drive, the integrated disk management system offers
three types of logical drives:

o   Type 1: contiguous logical drives Contiguous drives are just
    traditional logical drives.
o   Type 2: random logical drives Disk partitions are created
    horizontally across disks.  Files in a directory are scattered in
    different partitions.
o   Type 3: sequential logical drives Disk partitions are created the
    same way as type 2 logical drives; however, data of a file are
    cluster-interleaved on these partitions.

Figure 2 shows a storage system with all three types...