When you discover that you have suffered some data loss, the first decision is always if data recovery is possible. The subsequent action that needs to be taken depends on the answer to this, whether it is worth attempting data recovery or whether to find a way of managing the data loss.
Decide If Data Recovery is Possible
This can be a very difficult choice, especially if you are unsure what caused the data loss. The decision often becomes a commercial one of whether the information is actually worth the cost of recovery. Except in very extreme cases, the magnetization that stores the data will still be present on disc. Even in case where the computer has been burned, flooded, or crushed data recovery can still be possible, but at an extremely high price.
Types of Data and Their Effect on Data Recovery
The kind of data being recovered, also affect this decision. If you can recover, for instance, 90% of all lost data, and these files are pictures you will retrieve 9 out of 10 pictures; this can be considered a success. On the other hand, if the files are database tables and only 90% can be recovered the entire database is corrupted. The higher the dependency and interaction between the data files, the worse the effects of even a small amount of missing data will be.
Is It Logical or Physical Data Recovery?
There are two distinct procedures in data recovery: Physical data recovery is the extraction of the raw data from a damaged disc, logical data recovery means the rebuilding of damaged data files. Pure logical data losses are usually caused by operator error. The accidental deletion of files, accidental drive formatting, or it may be from a malicious virus attack. Physical data recovery from a drive that has failed mechanically may not need any subsequent logical reconstruction if it can be successfully repaired, though in practice many physical repairs are followed by logical reconstruction if some data is permanently lost due to damaged disc surfaces.
The Time Element in Logical Data Recovery
It is easy to underestimate the time element in data recovery, but losing data for a week is effectively losing the data forever. A single file that has been accidentally, permanently, deleted rather that being moved to the Recycle Bin or by emptying the Recycle Bin, is marked in the directory entry with E5. This frees the associated FAT entry and the as the location of the deleted file is no longer protected by the file system those locations are available for recycling the next time the OS needs to create a new file. The problem is that in any computer, files are continually being created. Many computer processes write to log files, and browsing even a single Website will download several files. Any of these could overwrite the deleted files making recovery much more difficult.
NOTE: DO NOT ATTEMPT DATA RECOVERY YOURSELF! YOU MAY RISK THE POSSIBILITY OF FULL DATA RECOVERY. ALWAYS CONSULT A DATA RECOVERY PROFESSIONAL. You can call Data Recovery Doctor to get professional FREE advice on what steps you need to take in order to successfully recover your data. Call 0207 516 1077.
Basic Data Recovery
Have you ever wondered how much data is stored in your PC, and how much time and energy would go into its recovery? Your computer almost certainly contains a lot of personal data – financial data, names, addresses, and telephone numbers, bank account information, photographs and much more. It may seem safe, but accidents do happen!
Why Did the Data Go?
The three most common causes of total data loss are a failure of your operating system, a mechanical malfunction of your hard drive, or a failure in the software that controls your hard drive. Should any of these happen, there are some data recovery steps you can take yourself, and if these fail there are plenty of data recovery specialists to choose from. You should consider that attempting to restore lost data to your hard drive carries a risk of causing more damage to it, making further data recovery more difficult or impossible.
Data Recovery after Operating System Failure
An operating system failure is a failure to recognize your hard drive; this usually shows as a Disk Boot Failure error message on start up. This means your hard drive has a problem. Either it has lost its logical format or it has developed a mechanical or electronic failure.
Data Recovery after a Mechanical Failure
An imminent mechanical disc failure announces itself by your hard drive making unexpected noises while accessing data. If you hear any, it is probably a mechanical failure of one of the many components in your hard drive. If this happens do not try to service the drive yourself!
Logical Data Recovery Methods
Logical data recovery is rebuilding files that have been damaged or corrupted by user error or virus attack, rather than repairing hard drives that have been physically damaged. In this situation the BIOS still recognizes the drive, but returns a read error when trying to access data.
Data Recovery from Fragmentation
Accidental file deletion, formatting, or partition deletion can result in a missing File Allocation Table entry. If the file size is smaller than the cluster size (clusters are commonly 32 KB, but it varies with drive size) you should get a 100% recovered file as you do not actually need the FAT entry. Larger files are usually allocated in consecutive clusters, and most data recovery software assumes this when it rebuilds files without a FAT entry. This will work for most types of files, but runs into problems with files that grow over time. Files like this are invariably fragmented, allocating consecutively is impossible due to other files taking the intermediate clusters. There are some important files that fall into this category, such as Databases, Email files, large text documents, and directories.
Data Recovery is Not Feasible after Overwriting
When a file’s allocation has been overwritten by another file, data recovery is practically impossible. It is theoretically possible to use highly advanced technology such as MFM (Magnetic Force Microscope), to read the rest magnetization, but it is extremely expensive and not very reliable. If a file has been overwritten more than once, even this level of technology cannot help. File ‘shredder’ software relies on this to delete files beyond recovery, by simple overwriting the deleted file several times.
How is a Hard Drive Recovery Done?
When your hard drive is ruined, the obvious question to ask is, “how do you get my data back? ” Despite what data recovery businesses may tell you, it is not done by black magic nor is it anything approaching rocket science, it has more to do with having the right equipment, and enough knowledge to know what to do with it.
Logical Hard Drive Recovery
Generally speaking, the first thing a hard drive recovery business will do when they receive a hard drive is to evaluate it to determine what recovery method will be required. If the drive failure is a software problem, they will perform a scan of the drive to try and repair the file system. In some cases a partition can be repaired, restoring the hard drive to its status prior to the drive failure. If this cannot be done, they will do a very low-level scan, searching every sector of the hard drive for files. Once they have located a lost file, it will be copied onto the media of your choice, this is usually a CD-ROM, a DVD-ROM, or ideally onto another hard drive. This type of Logical hard drive recovery takes a great deal of time, particularly if the hard drive is close to physical failure. It is not unusual for scanning to take a whole day, and recovering any files that are found to take another.
Physical Hard Drive Recovery
If your hard drive is suffering from a physical failure, the recovery method is considerably more difficult. There are two discrete forms of physical failure; electronic and mechanical. When recovering data after a physical failure, a major hurdle is getting the correct parts to get the drive going again. A problem with hard drives is that if you have, for example, a 60GB Maxtor Hard Drive you will need another, identical, 60GB Maxtor Hard Drive to salvage parts from. If it is the printed circuit board that has failed on your hard drive an identical circuit board is required to retrieve the necessary circuit components for replacement, because in most case it is not possible to swap the damaged circuit with the new one. Repairs of this nature require good soldering skills and a thorough knowledge of electronics to be successful.
Hard Drive Recovery Environment
You will see “Class 100 Clean Room” in a lot of advertising by hard drive recovery professionals. A Class 100 Clean Room maintains an air purity of less than 100 airborne particles over 0.5 microns in diameter in each cubic foot of air. This is to protect the sensitive internal components of hard drives. Whenever a hard drive is being worked on, a minimum of Class100 clean room should be used.
Hard Drive Recovery Time
The time taken for a hard drive recovery is usually 5-10 working days for a physical recovery (though if components are not readily available it may take weeks! ), 3-5 for a logical problem. An express service is often available, at a higher price.
Initial Steps in Hard Drive Recovery
If you find that your hard drive is no longer functioning, remember that a hard drive recovery is nearly always possible, so there is no need for panic. Data loss is not unusual and in nearly all cases the data can be recovered. Only in severe cases involving platter damage, magnetic degradation, or over-write of a file will the data be practically unrecoverable, and even in these cases a hard drive recovery by MFM photography may be possible if the data is valuable enough to justify huge expense.
Having said that, there are steps you can take to minimize further data loss and greatly increase your chances of successful hard drive recovery
What to do after a hard drive ‘crash’
If you find that you are unable to boot to the operating system, and you can no longer see the hard drive in the BIOS, there is a strong possibility that your hard drive has crashed. In this case you should shut the whole system down immediately. If there is some physical problem with the hard drive, it will be made a lot worse if you run power through the hard drive attempting to reboot the system. If the head stack inside your drive is damaged, trying to run it will cause additional damage to the surfaces of the platters in your hard drive, and this is where the data you are wanting to recover is stored.
Initial Steps in Hard Drive Recovery after Corruption
If you have accidentally reformatted your hard drive, or accidentally deleted a file or folder, once again you must not write any new information onto your drive. The files you have deleted are still intact somewhere on the drive. Deleting a file simply means removing the location tag for that file, allowing that area of the drive to be over-written. If you add any new data it is possible that it will over-write your lost data effectively losing it forever.
If you believe a partition has become corrupted on your hard drive, it is very important NOT to try and re-install your operating system or add any new data to the drive. If you have accidentally deleted a partition, attempting to restore it by formatting the drive will not recover your data; it will only result in the addition of an empty partition. If you experience a single file corruption, any attempt to create a new file with the same name will partially over-write the file, greatly decreasing your chances of a full recovery.
You can call Data Recovery Doctor to get professional FREE advice on what steps you need to take in order to successfully recover your data. Call 0207 516 1077.