Chapter 2: Intelligent Disk Subsystem
Content
Architecture of Intelligent Disk Subsystems
Hard disks and Internal I/O Channels
JBOB: Just A Bunch Of Disks
Storage Virtualization using RAID and different RAID levels
Caching: Acceleration of Hard Disk Access
Intelligent disk subsystems
Availability of disk subsystems
, Intelligent Disk Subsystem
Hard disks and tapes are currently the most important media for the storage of
data. When storage networks are introduced, the existing small storage devices are
replaced by a few large storage systems (storage consolidation).
For example, individual hard disks and small disk stacks are replaced by large
disk subsystems that can store between a few hundred gigabytes and several ten
petabytes of data, depending upon size.
Furthermore, they have the advantage that functions such as high availability,
high performance, instant copies and remote mirroring are available at a
reasonable price even in the field of open systems (Unix, Windows, OS/400, Novell
Netware, MacOS).
, 2.1 Architecture of Intelligent Disk Subsystem
A disk subsystem can be visualised as a
hard disk server.
Servers are connected to the connection
port of the disk subsystem using
standard I/O techniques such as Small
Computer System Interface (SCSI), Fibre
Channel or Internet SCSI (iSCSI) and can
thus use the storage capacity that the
disk subsystem provides.
Fig: Servers are connected to a disk
subsystem using standard I/O techniques.
, 2.1 Architecture of Intelligent Disk Subsystem (cont..)
The internal structure of the disk subsystem is
completely hidden from the server, which sees
only the hard disks that the disk subsystem
provides to the server.
The controller can significantly increase the data availability and data access
performance with the aid of a so-called RAID procedure. Furthermore, some
controllers realise the copying services instant copy and remote mirroring and
further additional services. The controller uses a cache in an attempt to accelerate
read and write accesses to the server.
Content
Architecture of Intelligent Disk Subsystems
Hard disks and Internal I/O Channels
JBOB: Just A Bunch Of Disks
Storage Virtualization using RAID and different RAID levels
Caching: Acceleration of Hard Disk Access
Intelligent disk subsystems
Availability of disk subsystems
, Intelligent Disk Subsystem
Hard disks and tapes are currently the most important media for the storage of
data. When storage networks are introduced, the existing small storage devices are
replaced by a few large storage systems (storage consolidation).
For example, individual hard disks and small disk stacks are replaced by large
disk subsystems that can store between a few hundred gigabytes and several ten
petabytes of data, depending upon size.
Furthermore, they have the advantage that functions such as high availability,
high performance, instant copies and remote mirroring are available at a
reasonable price even in the field of open systems (Unix, Windows, OS/400, Novell
Netware, MacOS).
, 2.1 Architecture of Intelligent Disk Subsystem
A disk subsystem can be visualised as a
hard disk server.
Servers are connected to the connection
port of the disk subsystem using
standard I/O techniques such as Small
Computer System Interface (SCSI), Fibre
Channel or Internet SCSI (iSCSI) and can
thus use the storage capacity that the
disk subsystem provides.
Fig: Servers are connected to a disk
subsystem using standard I/O techniques.
, 2.1 Architecture of Intelligent Disk Subsystem (cont..)
The internal structure of the disk subsystem is
completely hidden from the server, which sees
only the hard disks that the disk subsystem
provides to the server.
The controller can significantly increase the data availability and data access
performance with the aid of a so-called RAID procedure. Furthermore, some
controllers realise the copying services instant copy and remote mirroring and
further additional services. The controller uses a cache in an attempt to accelerate
read and write accesses to the server.
