Ⅱ.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, 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.
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Copyright © 2005-2006 CHENGDU YIWO Tech Development Co.' Ltd. All Right Reserved Data Recovery Book V1.0 (Visit http://www.easeus.com for more information)
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: “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, 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.
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Copyright © 2005-2006 CHENGDU YIWO Tech Development Co.' Ltd. All Right Reserved Data Recovery Book V1.0 (Visit http://www.easeus.com for more information) 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
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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. 5.SAN
SAN, called Storage Area Network or Network behind servers, is specialized, high speed network attaching servers and storage devices. A SAN allows "any to any" connection across the network, using interconnect elements such as routers, gateways, hubs and swithes. It eliminates the traditional dedicated connection between a server and storage, and concept that the server effectively "owns and manages" the storage devices. It also eliminates any restriction to amount of data that a server can access, currently limited by the number of storage devices, which can be attached to the individual server. Instead, a SAN introduces the flexibility of networking to enable one server or many heterogeneous servers to share a common storage "utility", which may comprise many storage devices, including disk, tape, and optical storage. And, the storage utility may be located far from the servers which use it.
6.NAS
NAS is Network Attached Storage. It can store the quick-increased information
.Backup means to prepare a spare copy of a file, file system, or other resource for use in the event of failure or loss of the original. This essential precaution is neglected by most new computer users until the first time they experience a disk crash or accidentally delete the only copy of the file they have been working on for the last six months. Ideally the backup copies should be kept at a different site or in a fire safe since, though your hardware may be insured against fire, the data on it is almost certainly neither insured nor easily replaced.
7.Backup
Backup in time may reduce the danger and disaster to the lowest, thus data security can be most ensured. In different situations, there are different ways. Both backing up important data of system with hardware and backing up key information with cloning mirror data to different storage device can work well.
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, 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.
------------------------------------------------------------------------------------------------------------------------------------ 4
Copyright © 2005-2006 CHENGDU YIWO Tech Development Co.' Ltd. All Right Reserved Data Recovery Book V1.0 (Visit http://www.easeus.com for more information)
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: “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, 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.
------------------------------------------------------------------------------------------------------------------------------------ 5
Copyright © 2005-2006 CHENGDU YIWO Tech Development Co.' Ltd. All Right Reserved Data Recovery Book V1.0 (Visit http://www.easeus.com for more information) 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
------------------------------------------------------------------------------------------------------------------------------------ 6
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. 5.SAN
SAN, called Storage Area Network or Network behind servers, is specialized, high speed network attaching servers and storage devices. A SAN allows "any to any" connection across the network, using interconnect elements such as routers, gateways, hubs and swithes. It eliminates the traditional dedicated connection between a server and storage, and concept that the server effectively "owns and manages" the storage devices. It also eliminates any restriction to amount of data that a server can access, currently limited by the number of storage devices, which can be attached to the individual server. Instead, a SAN introduces the flexibility of networking to enable one server or many heterogeneous servers to share a common storage "utility", which may comprise many storage devices, including disk, tape, and optical storage. And, the storage utility may be located far from the servers which use it.
6.NAS
NAS is Network Attached Storage. It can store the quick-increased information
.Backup means to prepare a spare copy of a file, file system, or other resource for use in the event of failure or loss of the original. This essential precaution is neglected by most new computer users until the first time they experience a disk crash or accidentally delete the only copy of the file they have been working on for the last six months. Ideally the backup copies should be kept at a different site or in a fire safe since, though your hardware may be insured against fire, the data on it is almost certainly neither insured nor easily replaced.
7.Backup
Backup in time may reduce the danger and disaster to the lowest, thus data security can be most ensured. In different situations, there are different ways. Both backing up important data of system with hardware and backing up key information with cloning mirror data to different storage device can work well.
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