Solid State Devices (SSD) are based on new technologies, which are not fully understood, as they are proprietary and usually not revealed by their manufacturers. These technologies are complex and continuously evolving, creating a challenge for SSD data recovery software. Amongst them are encryption, TRIM, and over-provisioning.
How Does an SSD Work?
Many SSDs use encryption as default. It is aimed at securing the data stored in the device. The encryption mechanism used can be software or hardware-based. In order to access the data, encryption asks for specific credentials that must be known by the user. Failure to so do results in data inaccessibility. For example, Microsoft uses BitLocker, which allows for full disk encryption, and SanDisk memory sticks contain its proprietary Secure Access Vault.
TRIM is a process that cleans pages with invalid data. In TRIM-enabled SSDs drives, this operation is done in the background by the garbage collector. Some manufacturers, such as Intel, use custom firmware to implement it.
TRIM is described in the SATA protocol as having three different types: non- deterministic, deterministic read after TRIM (DRAT), and deterministic zeroes after TRIM (DZAT). Only DZAT does a full and permanent clean, by replacing the content with zeroes after deletion.
However, as drive re-mapping is done constantly in order to free addresses, data may actually remain intact, even though it is reported as cleaned. Microsoft provides a utility named fsutil, which can be used to check if the TRIM mechanism is automatically enabled or not. This utility is available from Windows 7 onwards.
Overprovisioning is a mechanism intended for increasing the SSD lifespan. It simply means adding some extra blocks that are reserved by the controller, and can be used to replace failed ones. For example, a device claiming to contain 120 GB, may in reality have more available storage space.
How These Technologies Affect SSD Data Recovery?
These technologies introduce an extra challenge to SSD data recovery.
Encryption makes necessary having the credentials. Due to this, experts advise to keep a copy of them in a secure place. If recently used, these credentials may be available in the RAM, and recoverable with dedicated software.
TRIM creates serious obstacles, especially if done automatically. In this particular case, even shutting down, after the command has been issued by the operating system, does not stop its execution. Once the computer is on again, the operating system will continue its operation. This is particularly important as Microsoft only uses DZAT in Windows. In other cases some data may be retrieved with specific hardware SSD data recovery tools.
Overprovisioning may affect SSD data recovery as some storage space may not be accounted as available or used.
How Can I Plan what to Do in Case of Data Loss?
The most crucial step is to stop using the device and to keep it in the best possible condition. The second step is to do an image of the device, and try to recover the lost data from this copy.
In this manner, the original source is kept unaffected by the recovery process. The third is to use an SSD data recovery software such as Disk Drill and scan the image. This application is available for Windows and Mac. It has a free download version and a Pro version.
How Can I Use Disk Drill to Recover Data from a SSD?
Disk Drill comes with two helpful functionalities: quick and deep scan. The first is useful when the data has been recently lost. With old deletes, deep scan is more convenient. However, a scan will only work if TRIM has not already cleaned the storage space.
The scan can be done, paused and the session saved. As the SSD data recovery process may take from minutes to hours, depending on the size of the device, this last functionality allows to stop the operation and continue later, without losing any work already done.
For Macs, if Guaranteed Recovery (GR) is enabled, some data may be retrieved. This functionality is provided only by Disk Drill. It basically keeps a copy, which can be retrieved, of any file sent to a specified folder.
Otherwise, it is very important to take preventive measures such as regular back ups of critical information.
How Can I Create Back Ups with Disk Drill?
It is easy to create backups with Disk Drill. This SSD data recovery software comes with the “Back up into recoverable disk image” option. Thus, the information can be saved in a dmg, img or iso file, and later recovered with Disk Drill or any other image file software available in the market.