7 Data Protecting Technologies-1

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, data recovery 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)  phpto recovery 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.

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Resons for Data Loss

Actually,  there  are  various  reasons  that  cause  data  loss;  software,  hardware,  factitious,  natural, intended, unintended, all may cause data loss or damage on storage devices.
 
Generally,  There  are  two  main  reasons  for  data  problem:    software  and  hardware  whose corresponding reasons are software reason and hardware reason.

1.Software reason
Virus,  format,  mis-partition,  mis-clone,  mis-operation,  photo recovery for Mac network  deletion,  power-cut  during operation all may  be  the  software  reasons.  The  symptoms  are  usually  mis-operation,  read  error, can not find or open file, report no partition, not formatted, password lost and troubled characters.
 
A:  Computer  Viruses:  some  malicious  virus  programs  will  destroy  data,  overwrite,  or  erase  the data contents.
 
B:  Mis-format:  fast  or  completely  format  partition,  thus  changing  the  file  system  form  (NTFS, FAT32) of partition.
 
C: Mis-Clone: when backing up the hard disk, mis-clone or overlay the original data on hard disk.  
 
For  these,  we  can  use  software  tools  to  recover  it.  So  called  soft  recovery  means  data  can  be recovered  by  software,  not  referring  to  hardware  fixing  operation  for  its  fault  is  not  because  of hardware failure.  
 
The following are prompts that system can not start up normally:
 
Invalid Partition Table: Invalid partition table information.
Missing Operating System: phpto recovery“55AA” mark in DOS boot sector lost or DBR corrupted.
Disk Boot Failure: System file read failure. 
Bad or missing command interpreter: Can not find command.com file or ‘COMMAND.COM’ file corrupted.

Invalid system disk: DOS boot record corrupted.
Type  the  name  of  the  command,  Interpreter:  DOS  partition  mark  in  partition  table  error  or ‘COMMAND.COM’ file lost, corrupted.
Error Loading Operating System: Main boot startup program read boot sector unsuccessfully.
Not found any active partition in HDD: Active partition mark in partition table changed as inactive
partition mark.
 
2.Hardware reason
Sometimes  data  loss  is  because  of  hardware,  data recovery such  as  bad  sector  in  hard  disk,  power  cut,  head damage, circuit panel problem, etc.
 
When your hardware has some problems, you probably will find: the speed of hardware become slow, you cannot operate successfully; you cannot read data, etc, which are most often physical bad track failures.

Correspondingly, data recovery in hardware fix is considered as hard recovery, such as memory medium damage, track damage, hard disk scrape, head damage, electric machinery damage, chip burnout and so on..
 
The  most  distinct  feature  or  difference  between  soft  recovery  and  hard  recovery  is  whether  the memory medium itself can be normally accessed by fixing or replacing parts.  

BLOG:diskknowledge

Elementary knowledge of data recovery

1.Connotation of data
Connotation  of  data  is  comprehensive,  it  includes  not  only  multi-media  files  such  as  data
documents, images, voices that stored in file system or data base, but also hardware information,
network addresses and recover deleted files network services, which are used to deposit and manage those information.  
2.The essence of data recovery  
Data  recovery  means  retrieving  lost,  deleted,  unusable  or  inaccessible  data  that  lost  for  various
reasons.
 
Data recovery not only restores lost files but also recovers corrupted data.
On  the  basis  of  different  lost  reason,  we  can  adopt  different  data  recovery  methods.  There  are
software and hardware  reasons  that  cause  data  loss,  while  we can  recover data by  software  and
hardware ways.
 
Being different from prevention retrieve pictures and backup, data recovery is the remedial measure. The best way
to insure the security of your data is prevention and backup regularly. To operate and use your data
according to the normative steps, you can reduce the danger of data loss to the lowest.
3.The scope of data recovery
There are so many forms and phenomenon on data problem, we can divide the objects or scope of
data recovery according to different symptoms.  
 
System problem
The  main  symptom  is  that  you  cannot  enter  the  system  or  the  system  is  abnormal  or  computer
closes down. There are complex reasons for this, thus we need adopt different processing methods.
Reasons for this symptom may be the key file of system is lost or corrupted, there is some bad
track  on  hard  disk,  the  hard  disk  is  damaged,  MBR  or  DBR  is  lost,  or  the  CMOS  setting  is
incorrect and so on.
 
Bad track of hard disk
There are logic and physical bad track. Logic bad track is mainly caused by incorrect operation,
and it can be restored by software. While physical bad track is caused by physical damage, which
is real damage, we can restore it by changing the partition or sector. When there is physical bad
track, you’d better backup your data for fear that the data can not be used any more because of the
bad track.
 
Partition problem
If partition can not be identified and accessed, or partition is identified as unformatted, partition
recovery tools such as Partition Table Doctor can be used to recover data.
 
Files loss
If files are lost because of recover deleted photos on Mac deletion, format or Ghost clone error, files restoring tools such as Data
Recovery Wizard can be used to recover data.
Password loss Data Recovery E-Book V1.5 If  files,  system  password,  database  or  account  is  lost,  some  special  decryption  tools  that
correspond to certain data form such as Word, Winzip can be used.
 
Files repair
For  some  reasons,  some  files  can  not  be  accessed  or  used,  or  the  contents  are  full  of  troubled
characters,  the  contents  are  changed  so  as  they  can  not  be  read.  In  this  condition,  some  special
files restoring tools can be tried to restore the files.
4.The principle of data recovery  
Data recovery is a process of finding and recovering data, in which there may be some risk, for no
all  situations  can  be  anticipated  or  prearranged. It  means  maybe  there  will  be  some  unexpected
things happen. So you need reduce the danger in data recovery to the lowest:
 
Backup all the data in your hard disk
Prevent the equipment from being damaged again
Don’t write anything to the device on which you want to recover data  
Try to get detailed information on how the data lost and the losing process
Backup the data recovered in time.