Solid State Drives and Deleted Files: Gone for Good?

Nothing can quite describe the panic, fear and trepidation experienced when you realise you’ve deleted an important file and there’s no way of getting it back. Shock. Horror. Dread. Now what?

When the PC was first introduced few were aware that deleted files could be recovered, but over time enthusiasts figured out at that deleted files could generally be recovered. The reason being that when a file was deleted it was the index entry which is deleted and not the actual file itself, and more often than not, the actual file remained undamaged and intact. This was seen as a Hail Mary in the IT industry and saved many frantic customers from potentially disastrous consequences as there were and are various data recovery solutions. However, there are certain times when data recovery isn’t that simple.

When it comes to Solid State Drives, or SSDs as they are often referred to, if the file is deleted, it’s gone for good. Why? Standard hard drives write over existing data, however, in the case of the SSD, it first needs to erase any existing data and only then writes the new data. While the writing or reading of a data block happened at an acceptable, albeit slow pace, erasing a data block was a very slow process and over time, first generation SSDs became slower and slower. In order to speed things up, newer SSDs have introduced ‘garbage collection’ which involves pre-emptively erasing recently freed up blocks during their idle time. This process is found in all current SSDs.

Initially, operating systems, such as Windows, posed problems for SSDs due to poor communication and understanding between the two. When a file was deleted in Windows, the SSD didn’t recognise the deletion and still considered that space to be in use. In order to overcome this problem, SSD manufacturers thus introduced a feature called TRIM which enables effective communication between the SSD and operating system and informs the SSD of free data blocks as and when they become available. The SSD then adds these blocks to the list of blocks to be deleted and thus a deleted file is totally unrecoverable within moments of its deletion.

However, like most things in life, there are exceptions, such as: when the operating system doesn’t support TRIM; if you’re using an older, first generation SSD or SSD which is formatted with FAT16 or FAT32; using a SSD inside an external USB, Firewire enclosure or the majority of NAS boxes; if your file system corrupted and the volume isn’t accessible or recognised. TRIM is also not supported by PCI Express SSDs, encrypted volumes or SSD RAID arrays.

As prices come down SSDs are becoming more commonplace and as they do we become increasingly aware of their benefits, however, as there are a few negatives which we mentioned above.

If you are at all unsure about whether or not data can be retrieved on your solid state drive, or if you would like a second opinion, please do not hesitate to contact us.

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