A solid state disk – SSD for short – differs from standard hard drives to the chassis size and interface. In contrast to the traditional media, data are not stored or read out on magnetized rotating disks by means of movable read / write heads. SSDs store data in semiconductors. This saves the drive any moving parts and makes it – to a certain extent – insensitive to impacts or rapid movements of a different kind.
Possible causes of problems with SSDs
Unlike the volatile main memory of a computer, information is retained in the SSD even after switching off the supply voltage, so that power failures can not ensure data loss. Mechanical errors, the most common cause of inconvenience with conventional hard disks, can thus be almost completely excluded with SSDs. However, logical errors occur much more frequently, whether by fatigue of the material or by the maximum possible write operations per cell.
Firmware problems after power failures
Another popular way to make data unattainable is the accidental deletion of files or directories on the disk - for example, without using the recycle bin.
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However, deleted data in most cases is not, or at least not completely lost. Deleting via the file system of a computer simply releases cells for overwriting without actually deleting them at the same moment. As long as no new data is written into the drive, there is a good chance that the contents of the affected cells can be read out.
Controller Internal Encryption
Of course, SSDs are also exposed to the trivial causes of data loss, such as human error, malware, or programs that are running incorrectly. These may prevent any information stored on SSDs from being erased, corrupted, or rendered unusable. In contrast to magnetized disks in hard disks, from whose sectors data can still be read even if the remaining logic or mechanics are lost, SSDs are somewhat more complicated.
It is equally obvious that electrical and electronic components can also fail, be mechanically damaged or rendered unusable due to overvoltage in the new drive types. The challenge with SSDs is now to put together the information distributed over the individual cells in such a way as to create a meaningful file or at least a fragment with which the user or an application can start something. Because each of the many SSD vendors has the same number of controller types and types, each drive of this type also distributes the data to the free or over-marked cells in a different way.
Rescue programs or even deeper rescue logics must emulate exactly this type of controller. This is much more complex than the data recovery of hard disks, and you need special hardware and software that can only be found at specialized companies. It does not have to be mentioned specifically that money is really needed.
The control software running on the controller of a SSD, called "firmware", is used to accept and store data in the cells, retrieve them, send them over the interface, and perform secondary tasks, such as encryption and optimal placement of the information in the semiconductors responsible. The medium itself, ie, the cells with the stored information, is hardly susceptible to sudden power failures. However, the software of the controller is as sensitive as any other program in another memory. What does this mean for practice?
If a specific action is not completed at the time of a power failure, the affected information is not stored: This will damage the entire file! This is especially possible when new information is being written which has been accepted by the interface to the computer and has not yet been stored in the memory cells. Many SSDs dispense with an acknowledgment of the actual storage of the data in the memory cells in favor of a higher overall performance, and are content with providing the computer with information (from the interface to the controller) rather than after storing it in a cell "Acknowledge").
If, during this time, the operating voltage drops out and the buffer (a condenser with correspondingly high power) installed to intercept this problem is too small, information is lost. An example of this was the so-called 8 MByte bug of some Intel drives.
SSDs from almost all well-known manufacturers use logics to communicate with the hard disk interface of the computer, whose chip has an internal encryption option for the stored information. This encryption can not be switched off for many affected drives so that the stored data can be saved only with great difficulty or at all if the controller is damaged. In addition, the manufacturers of these types do not give the keys themselves, even in the event of a requested data recovery, so that restoration is impossible.
Some examples of good "rescue" media are SSDs with S4LJ204X01 and S4LN021X01, Indilinx, Mavell and JMicron controllers. In this context, it is necessary to disqualify drives, especially with older Sandforce controllers (in particular the 2281), where the saving of the stored information is no longer possible afterwards due to the internal encryption.
So if you want to be safe and get an internally proprietary encrypted SSD or switch on this mechanism in a drive, it should significantly reduce your backup cycles. The best thing to do is, of course, an incremental backup after each storage of important files, but at least a mid-day and an evening backup is recommended so that a maximum of half a day's work is destroyed.
First measures and data recovery
If an SSD does not do what it is supposed to do, ie no longer storing data correctly or causing errors when reading the same, you should not be rash, as always. Unlike the traditional hard drive, the SSD does not make any noise when it is no longer comfortable. Only the corruption of the stored information can be taken from the fact that something is in the arrogance. In the worst case, the medium is no longer accessible due to a defective interface or a faulty controller.
If your computer is still in contact with the SSD, so you can still read data, first avoid any write accesses at all costs. This means that you should close all applications, without saving any new or changed files, which may have previously been saved, to other media. This will prevent any cells that have already been opened for overwriting to be filled with new information and to erase old data irretrievably.
Software for data recovery
Then, with one of the numerous tools offered for this area, you can try to revive still reconstructable information. Also here, you should make sure that a different hard disk or an external medium is available for the storage of the saved data, in order not to have to write to the damaged SSD in this case too.
If the computer does not get any contact with the drive, you should first remove it and try to connect it to another computer via a USB-to-SATA connection. This can be used to prevent the hard disk controller of your computer from being the cause of the problem. If the drive does not work externally on another computer, you have no other option but to pass it to a professional lab for rescue.
Only such a company has the possibility to connect the data carriers (in our case the semiconductors with the memory cells) from the drive, to a corresponding working controller and to reconstruct the data stored there in full or at least partially. However, this type of rescue does not cost very little: With Kroll Ontrack, the price for the diagnosis is 90 euros, the data recovery costs 299 euros. Upwards, the price can always be fast, depending on the problem.
Conclusion: Without backup it does not work!
And even specialized companies can not guarantee 100% to recover the lost or damaged data. This is the reason why here again the reference to the only cheap alternative is the backup of all important files, several times a day, and if only a USB stick or an external hard disk is needed.
The likelihood that both media, ie external memory and SSD, simultaneously deny the service is negligible. At first glance, this seems to be a cumbersome procedure, but it is still cheaper than saving the data by a specialized company. And it also does not cost days or weeks, but in the worst case, only hours - namely the purchase of a new SSD.
As mentioned above, deleted files from SSDs can be restored whenever the cells they occupy have been released for overwriting, but have not yet been described with new information. In principle, one goes here as with the restoration of files on conventional hard disks. First, the application scans every accessible and readable area of the SSD on data or data fragments, then it builds a list of recoverable files and allows the user to select them for reconstruction.
In most cases, an estimate is also given of how likely full recovery is. Then the location for the recovered files is queried and the process is started. Depending on the intensity of the search, the size of the medium, and the level of the over-execution already done, recovery may take several hours.
Many of these applications are available in several versions that support different types of restoration. While the mostly free versions for the home user only search for deleted files, make them usable again, and also have limitations on the volume of the data processed, the professional tools offer no restrictions and sometimes even the ability to read data from damaged RAID groups .
For example, EaseUS Data Recovery Wizard (Free, Standard and Pro version), DiskRecovery (Professional, Admin and Tech level) or DiskInternals NTFS Recovery, which is also available as trial output with certain limitations.
In the end, even more than for hard disk drives, SSDs do not have to replace a regular backup of the important data - and, of course, an image of the installed system drive. The effort to reconstruct the fast media data, if they have not just been deleted, but the controller or a memory chip have blessed the temporal is much too high, must be left to specialists and is expensive.
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