Access
Access is the action of obtaining data from or writing data into a data
storage device.
ANSI
American National Standards Institute.
ATA
Advanced Technology Attachment. ATA was originally defined as a standard
for embedded fixed disk storage on IBM AT compatible PCs and is now the
dominant storage interface.
Bit
Bit is an abbreviation for binary digit. A bit can only contain the
value 1 or 0. The bit is the basic data unit for digital computers.
Buffer
The buffer is the storage area used to temporarily store data so that a
difference in data transfer rates and/or data processing rates between
sender and receiver can be compensated.
Byte
A
byte consists of eight bits.
Cache
Like the buffer, the cache is DRAM (dynamic random access memory) on the
hard drive used to store temporary data that has recently been accessed
or data waiting to be written to the disk.
Capacity
Capacity is the amount of data that can be stored in a given storage
device, usually expressed in bytes.
Channel
A
channel (referring to that on a data cable) is a collection of
electronic circuits used for data writing and reading processes to and
from magnetic media.
Data
Data is an ordered collection of information.
Gigabyte (GB)
A
unit of storage. 1 GB can mean either 1,000,000,000 bytes using the
decimal system or 1,073,741,824 bytes using the binary system. Most hard
drive manufacturers define 1GB as 1,000,000,000 bytes, while the
operating system will treat 1GB as 1,073,741,824 bytes. This is why the
operating system shows the hard drive’s capacity as different to the
manufacturer’s claim.
Jumper
Jumpers are used to set a hard drive’s attributes, such as Master/Slave.
A jumper is in essence a simple on/off switch and when placed over two
pins it is the same as closing a circuit. The combination of one or
several jumpers results in different settings.
Latency
Latency refers to the delay that occurs when requesting a specific
response. Less latency is better.
Megabyte (MB)
A
unit of storage. 1MB=1,000,000 bytes decimal or 1,048,576 bytes binary.
Hard drive manufacturers usually apply the decimal system while the
operation systems apply binary system of calculating storage capacity.
PATA
(Parallel
ATA), IDE/EIDE (Enhanced
Integrated Drive Electronics)
ATA is the
acronym for Advanced Technology Attachment, and it has become an
industry standard hard drive interface for 15 years. ATA uses a 16-bit
parallel connection to make the link between storage devices and
motherboards, and is also called PATA to distinguish it from the newer
SATA standard. In additional, ATA is also known as IDE or EIDE (Enhanced
Integrated Drive Electronics). Currently the two most popular standards
for ATA hard drives are the ATA-6 (which is also known as Ultra ATA 100
or Ultra DMA 100) and ATA 133. The maximum bandwidth for the former is
100MB/s, and 133 MB/s for the latter.
SATA
(Serial ATA)
SATA is an
interface standard for connecting hard drives to computer systems, and
is based on serial signaling technology. The advantages over PATA
include longer, thinner cables for more efficient airflow within a
computer chassis, fewer pin conductors for reduced electromagnetic
interference, and lower signal voltage to minimize noise margin. The
bandwidth of SATA is also far improved over today’s PATA - the SATA 1.0
can reach a maximum of 1.5Gb/s (150MB/s), while the latest SATA 2.5
standard can support up to 3Gb/s (300MB/s). As a result of so many
advantages, the SATA interface is gradually replacing PATA as the
mainstream hard drive interface in the personal storage market.
SCSI
(Small Computer
System Interface)
SCSI is a standard interface for transferring data between devices and
computers. Thanks to its outstanding ability
to compartmentalize diverse operation, SCSI is very suitable for
multitasking operating environments. Also, SCSI enhances critical
performance in situations where more than one device is connected.
Before serial signaling technology was applied into the SCSI field, all
SCSI interface standards used parallel technology to transfer data.
RAID
(Redundant Array of
Independent/Inexpensive Disks)
RAID is a method of using multiple hard drives together for data
storage. A RAID system with multiple hard drives appears as a single
drive to the operating system. Depending on the RAID level, the benefits
provided by RAID is one or more of the following: better throughput,
fault-tolerance or capacity (or something else) when compared to single
hard drive.
1.
RAID level 0 (or RAID 0) is known as striping, where data is striped
across multiple hard drives. RAID 0 provides the most advanced
throughput and capacity, but offers no fault-tolerance.
2.
RAID level 1 (RAID 1) is known as mirroring, which stores the exact same
data within at least two hard drives, this method shows excellent
fault-tolerance and reliability, but delivers less capacity efficiency.
3.
RAID level 0+1 and RAID 1+0
are both striping and mirroring, providing good fault-tolerance and
throughput all at the same time.
There are other RAID levels available too, such as RAID level 5 and RAID
level 6.
Read
Reading is the action of access a storage location and obtaining the
stored data.
Write
Writing is the action of recording data on a storage device.
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