Connectivity
• Interconnection between hosts or between a host and any storage devices
Connectivity Protocol
• Interconnection between hosts or between a host and any storage devices
•Physical Components of Connectivity are:
–Bus,
port and cable
Connectivity Protocol
• Protocol = a defined format for
communication between sending and receiving devices
–Tightly
connected entities such as central processor to RAM, or storage buffers to
controllers (example PCI)
–Directly
attached entities connected at moderate distances such as host to storage
(example IDE/ATA)
–Network
connected entities such as networked hosts, NAS or SAN (example SCSI or FC)
Popular
Connectivity Options: PCI
•PCI is used for local bus system within a
computer
•It is an interconnection between
microprocessor and attached devices
•Has Plug and Play functionality
•PCI is 32/64 bit
•Throughput is 133 MB/sec
•PCI Express
–Enhanced
version of PCI bus with higher throughput and clock speed
Popular
Connectivity Options: IDE/ATA
• Integrated Device Electronics (IDE) /
Advanced Technology Attachment (ATA)
– Most
popular interface used with modern hard disks
– Good
performance at low cost
– Inexpensive
storage interconnect
– Used
for internal connectivity
• Serial Advanced Technology Attachment
(SATA)
– Serial
version of the IDE /ATA specification
– Hot-pluggable
– Enhanced
version of bus provides upto
6Gb/s (revision 3.0)
Popular
Connectivity Options: SCSI
•Parallel SCSI (Small computer system
interface)
–Most
popular hard disk interface for servers
–Higher
cost than IDE/ATA
–Supports
multiple simultaneous data access
–Used
primarily in “higher end” environments
–SCSI
Ultra provides data transfer speeds of 320 MB/s
•Serial SCSI
–Supports
data transfer rate of 3 Gb/s (SAS 300)