Too TRIM? When SSD Data Recovery is Impossible

Solid-state drives (SSDs) have revolutionized the way we store data, offering significant improvements in speed and performance over traditional mechanical hard drives. However, with these advancements come certain drawbacks, particularly when it comes to data recovery. One lesser-known issue is the impact of the TRIM command on data recovery. Once a file is deleted on a TRIM-enabled SSD, the data is gone for good. This article delves into the workings of TRIM, its benefits, and its downside when it comes to data recovery.

What is SSD Trim?

TRIM is a command for the ATA interface that helps manage the way data is stored on an SSD. As you use your drive, changing and deleting information, the SSD needs to ensure that invalid information is deleted and that space is available for new information to be written. TRIM tells your SSD which pieces of data can be erased. The command is different for other interfaces and goes by different names in different operating systems, but the action is usually referred to as “TRIM.” Regardless of the name, TRIM works with Active Garbage Collection to clean up and organize your solid-state drive. While TRIM is beneficial, it is not mandatory. Some operating systems do not support TRIM, so SSD manufacturers design, create, and test their drives assuming that TRIM will not be used.

 

What does TRIM do?

The TRIM command informs the SSD that specific areas contain data no longer in use, which appears deleted from the user’s perspective. Due to the way SSDs read and write data, it isn’t deleted immediately. Instead, the SSD marks these areas as unused. The TRIM command allows the drive to remove this data, and during idle times, Active Garbage Collection deletes it. Without TRIM (as before Windows 7), the SSD wouldn’t know certain sectors contained invalid data until new data needed to be written there, requiring erasure of the old data first, which takes more time. TRIM and Active Garbage Collection enable faster write operations and extend the SSD’s lifespan. Constant writing and erasing in the same NAND cells degrade them. For optimal longevity, cells should be used evenly, a process called wear leveling. TRIM helps manage which cells can be erased during idle times, organizing data-filled and empty cells to minimize unnecessary erasing and rewriting.

The Reason for TRIM, and its Downside

As solid-state drives began to catch on, a major flaw was discovered: speed degradation. At first, it was believed that only certain SSDs were at risk, but it turns out that pretty much every model on the market shared the same inherent issue. Almost all storage devices handle files we delete similarly. Once a file is deleted, the link to that data, stored in the storage device’s indexer, is simply wiped clean. The data remains intact until that exact block is overwritten with fresh data. This method allows for data recovery, at least until the block is overwritten.

 

Mechanical drives can overwrite data with virtually no performance penalty, so their performance remains stable over time. In contrast, SSDs experience performance degradation due to how NAND flash works. When data is written to various blocks, deleting data from the same block doesn’t completely remove it, leading to a cluttered state. Garbage collection helps by occasionally consolidating loose data into a convenient block, but it doesn’t solve the issue of an SSD writing more than a block’s worth of data. The SSD must first purge the data in the block before writing new data, unlike mechanical drives that simply overwrite old data. This is where TRIM comes in. First widely deployed with Windows 7, TRIM is an ATA command the OS issues to the SSD for requests like Delete, Format, or Discard. TRIM purges both the data and its link, leaving the block ready for use.

 

The Impact on Data Recovery

Once TRIM is issued, your chance of data recovery is essentially zero. Data recovery on hard drives and non-TRIM affected SSDs is relatively simple with a reliable recovery tool, provided the block hasn’t been overwritten since deletion. On a TRIM-enabled SSD, deleting a file and emptying the Recycle Bin/Trash makes data recovery impossible, even with forensics. Unlike mechanical hard drives, which store data magnetically, TRIM ensures data on NAND is permanently erased. Whether TRIM on a mechanical hard drive renders data unrecoverable is uncertain. For consumers, the data is likely unrecoverable, but experts with proper tools might succeed. NAND operates similarly to RAM; once the charge is lost, the data is gone.

Conclusion

While TRIM is an essential command that enhances the performance and longevity of SSDs, it comes with a significant downside: the impossibility of data recovery once a file is deleted. This makes it crucial for users to be aware of the implications of using TRIM-enabled SSDs and to take necessary precautions, such as regular backups, to avoid permanent data loss. Understanding the workings of TRIM and its impact can help users make informed decisions about their data storage solutions.