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Solid State Drives (SSD) have a garbage collection functionality which makes space from deleted files available. It is triggered

  • automatically by the drive
  • via a TRIM command sent by the OS

Is there a way to put an SSD in a state where the automatic garbage collection does not occur?

Having forensics data collection in mind, I would like to ensure that the checksum of the image does not change between collection exercises because of this functionality (all other precautions being in place).

  • Great question, have you contacted the manufacturer/s as I'm sure they'll know. – Chopper3 Nov 3 '15 at 8:48
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    SSD garbage collection happens internally in the SSD and is transparent to the OS, so images taken using "dd" for example would always be the same unless the OS explicitly modified a block through a write command (when you mount a filesystem for example). – André Borie Nov 3 '15 at 9:51
  • Unless, of course, the SSD's controller is botched. In which case you have (or are about to have...) bigger problems anyway. – a CVn Jan 26 '16 at 20:40
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There is no such way in any of the existing normal SSDs, you can minimize to zero the effect of garbage collection if you write only sequentially but other than that you have no control over the garbage collection.

There are talks about some SSDs with features that allow the host to hint to the SSD about overall intentions but these are just hints and the SSD can ignore them if it gets to an edge case internally.

Source: I'm working on SSD based products and am in discussions with SSD vendors about such topics as well.

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