As demonstrated in a series of articles published earlier in this blog, solid-state disks (SSD) tend to wipe deleted information on their own pace due to the way their garbage collection mechanism is designed. Wiped information cannot be recovered by any means, not even with expensive hardware, and not even by pulling flash memory chips out. It’s gone forever.
As you may already know, sometimes this does not happen – mostly because, for one reason or another, the TRIM command was not enabled at the time the data was deleted. If this is the case, information remains on the SSD drive the way it resides on ordinary hard drives, and is recoverable.
Situations where the TRIM command is not enabled include:
- Unsupported operating system. In Windows world, only Windows Vista, Windows 7 and Windows 8 (and their server versions) are TRIM-compatible. If an SSD was used in a PC running an older OS (e.g. Windows XP), the TRIM command was never issued.
- The file system. Even if the PC is running Windows, if you formatted an SSD drive with any file system other than NTFS, the TRIM command will not be issued. Windows only supports TRIM on NTFS formatted volumes.
- Connection type. Only those drives connected directly via SATA or eSATA will recognize the TRIM command. TRIM is not supported over USB or LAN. Therefore, remote and most external disks will behave just like ordinary hard drives (with the exception of external drives using an eSATA link).
- Storage configuration. SSD’s will not support TRIM if assembled into a RAID. Moreover, certain motherboards will not pass the TRIM command even to a stand-alone SSD drive if RAID support is enabled in BIOS for the SATA port connecting to the SSD.
- Deleted files were stored in a crypto container, and the TRIM option was disabled within the container’s settings (disabling TRIM is their default behavior due to security concerns).
- TRIM is disabled in OS drivers.
Disabling TRIM greatly reduces the SSD’s writing speed, increases its wear level and reduces its lifespan. Disabling TRIM or using SSD drives in configurations where TRIM cannot be used is generally not recommended by their manufacturers. However, if data loss did occur, it’s worth checking if TRIM was actually enabling – or not.
Finally, certain types of files, such as resident files and files kept in cluster slack space, will not be affected by the TRIM command even if TRIM was enabled. Such files can be recovered by using comprehensive disk scan (PowerSearch), a feature of certain higher-grade data recovery tools such as The Undelete or HDD Recovery Pro.