Todos os arquivos podem ser excluídos com segurança , contanto que você use a ferramenta correta . Por exemplo O SDelete da Sysinternals é capaz de lidar com isso
On NTFS drives SDelete's job isn't necessarily through after it allocates and overwrites the two files. SDelete must also fill any existing free portions of the NTFS MFT (Master File Table) with files that fit within an MFT record. An MFT record is typically 1KB in size, and every file or directory on a disk requires at least one MFT record. Small files are stored entirely within their MFT record, while files that don't fit within a record are allocated clusters outside the MFT. All SDelete has to do to take care of the free MFT space is allocate the largest file it can - when the file occupies all the available space in an MFT Record NTFS will prevent the file from getting larger, since there are no free clusters left on the disk (they are being held by the two files SDelete previously allocated). SDelete then repeats the process. When SDelete can no longer even create a new file, it knows that all the previously free records in the MFT have been completely filled with securely overwritten files.
Certamente você escolheu a ferramenta errada porque, se você leu a documentação, verá que
Recuva cannot:
- ...
- Securely delete certain very small files that are held in the Master File Table (MFT) and files of zero-byte length.
Introducing Recuva - What it can and can't do
Why 640 bytes? Thought it was 512 bytes maximum for MFT entries for wiped files?
O tamanho dos arquivos que podem ser armazenados na MFT (chamados arquivos residentes ) varia dependendo cada arquivo, cada sistema e quais informações são armazenadas na MFT. Quanto mais dados são usados para metadados na MFT, menos resta para o arquivo , portanto não há limite definido, mas de acordo com a Microsoft normalmente
Files smaller than approximately 900 bytes are stored within the directory entry at the MFT
The figure MFT Entry with Resident Record shows the contents of an MFT record for a small file or folder. Small files and folders (typically, 900 bytes or smaller) are entirely contained within the file’s MFT record.
Eu criei um exemplo de arquivo de 1000 bytes com metadados muito mínimos que são armazenados completamente na MFT . Mas assim que adicionei mais metadados ao arquivo (links físicos, nomes mais longos, fluxos, permissões ...), o espaço máximo que pode acomodar o arquivo residente reduz rapidamente