Ⅲ.Data Protecting Technologies

Ⅲ.Data Protecting Technologies
Data security and fault freedom of storage are paid more and more attention. People are attaching
more and more importance to developing new technologies to protect data.
1.SMART Technology
SMART, also called Self-Monitoring Analysis and Report Technology, mainly protects HD from
losing data when there is some problems on the HD. SMART drive can reduce the risk of data
loss, it alarms to predict and remind thus enhancing the data security.
2.SPS
Shake Protecting System, can prevent the head from shaking thus enhancing the anti-knock
characteristics of HD, avoiding damages caused by shake.
3.DFT
DFT, a kind of IBM data protecting technology, can check hard disk via using DFT program to
access the DFT micro codes in hard disk. By DFT, users can conveniently check the HD
operation.
4.Floppy disk array technology
Originally ‘Redundant Arrays of Inexpensive Disks’. A project at the computer science department
of the University of California at Berkeley, under the direction of Professor Katz, in conjunction
with Professor John Ousterhout and Professor David Patterson.
The project is reaching its culmination with the implementation of a prototype disk array file
server with a capacity of 40 GBytes and a sustained bandwidth of 80 MBytes/second. The server
is being interfaced to a 1 Gb/s local area network. A new initiative, which is part of the Sequoia
2000 Project, seeks to construct a geographically distributed storage system spanning disk arrays
and automated libraries of optical disks and tapes. The project will extend the interleaved storage
techniques so successfully applied to disks to tertiary storage devices. A key element of the
research will be to develop techniques for managing latency in the I/O and network paths.
The original (‘Inexpensive’) term referred to the 3.5 and 5.25 inch disks used for the first RAID
system but no longer applies.
The following standard RAID specifications exist:
RAID 0 Non-redundant striped array
RAID 1 Mirrored arrays
RAID 2 Parallel array with ECC
RAID 3 Parallel array with parity
RAID 4 Striped array with parity
RAID 5 Striped array with rotating parity
The basic idea of RAID (Redundant Array of Independent Disks) is to combine multiple
inexpensive disk drives into an array of disk drives to obtain performance, capacity and reliability
that exceeds that of a single large drive. The array of drives appears to the host computer as a
single logical drive. The Mean Time Between Failure (MTBF) of the array is equal to the MTBF
of an individual drive, divided by the number of drives in the array. Because of this, the MTBF of
a non-redundant array (RAID 0) is too low for mission-critical systems. However, disk arrays can
be made fault-tolerant by redundantly storing information in various ways.