4 ms·

Well to be fair, there is an entire layer of abstraction at the SSD controller level that does tons of black box magic. It allows the OS to treat the SSD as ano

Well to be fair, there is an entire layer of abstraction at the SSD controller level that does tons of black box magic. It allows the OS to treat the SSD as another other storage device without letting the OS know what is going on. So the combination of non-moving parts (making it hard/impossible to debug via physical inspection) combined with a tons of wear leveling/misc magic can defo make it seem like SSD's are magical.

hanikesn 8y ago
The exact same thing happens hard drives. There's a ton of magic going on.
- NikolaeVarius 8y ago
  Lots of extra magic happens in an SSD though https://www.youtube.com/watch?v=C5JoC4-qsO0 https://www.youtube.com/watch?v=C5JoC4-qsO0 https://www.forensicswiki.org/wiki/Solid_State_Drive_(SSD)_Forensics https://www.forensicswiki.org/wiki/Solid_State_Drive_(SSD)_F...
  - relieferator 8y ago
    Thanks for this youtube link. In the case of recovering deleted files from SSD's that have the trim command enabled (Forensics Writeblocker was used,) the following drives have a low probability of recoverability: Crucial, Intel, and Samsung (3core controller). Whereas Seagate, Supertalent (parallel ATA to SATA bridge chip,) OCZ, and Patriot; files could be recovered. If the drive is quick-formatted, and if trim is enabled, the data is completely gone on the following drives: Crucial, Intel and Samsung. The trim state impacts the most whether or not the data can be recovered. You can check if trim is enabled with the command: fsutil behavior query DisableDeleteNotify - if your result is 0, it is enabled (default).
- gpvos 8y ago
  Yes, but most technical people seem to have a mental model that explains most failures pretty well. Not so for SSDs, apparently.
Wowfunhappy 8y ago
Is there a good reason why we use separate SSD controllers instead of letting the primary cpu handle it? The obvious reason is backwards compatibility, but as more of computing moves to SSDs, is this still relevant? ZFS has shown that removing layers of abstraction with regard to storage can be beneficial.
- pixl97 8y ago
  https://azure.microsoft.com/en-us/blog/project-denali-to-define-flexible-ssds-for-cloud-scale-applications/ https://azure.microsoft.com/en-us/blog/project-denali-to-def...
- pjc50 8y ago
  That adds a round of latency, and makes it pretty much impossible to boot off the drive. The blocks aren't in the same order in the Flash as they are presented by its interface, and one of the main jobs of the controller is to re-order them. It would be an interesting product to have, a raw block API to a Flash device with all the temporary state stored on the host - but a hard one to sell, as it's not differentiated in any way.
  - blattimwind 8y ago
    There are host-managed SMR drives, which share a number of characteristics with flash storage.
- selectodude 8y ago
  Apple uses their T2 security enclave as the SSD controller and it's caused quite a stir.
  - joosters 8y ago
    I wonder if you can read any extra state out of the T2 as a result, e.g. more information on wear leveling, temporary read failures and so on, more than the standard SMART counters?

hanikesn 8y ago

The exact same thing happens hard drives. There's a ton of magic going on.

NikolaeVarius 8y ago
Lots of extra magic happens in an SSD though https://www.youtube.com/watch?v=C5JoC4-qsO0 https://www.youtube.com/watch?v=C5JoC4-qsO0 https://www.forensicswiki.org/wiki/Solid_State_Drive_(SSD)_Forensics https://www.forensicswiki.org/wiki/Solid_State_Drive_(SSD)_F...
- relieferator 8y ago
  Thanks for this youtube link. In the case of recovering deleted files from SSD's that have the trim command enabled (Forensics Writeblocker was used,) the following drives have a low probability of recoverability: Crucial, Intel, and Samsung (3core controller). Whereas Seagate, Supertalent (parallel ATA to SATA bridge chip,) OCZ, and Patriot; files could be recovered. If the drive is quick-formatted, and if trim is enabled, the data is completely gone on the following drives: Crucial, Intel and Samsung. The trim state impacts the most whether or not the data can be recovered. You can check if trim is enabled with the command: fsutil behavior query DisableDeleteNotify - if your result is 0, it is enabled (default).
gpvos 8y ago
Yes, but most technical people seem to have a mental model that explains most failures pretty well. Not so for SSDs, apparently.

Wowfunhappy 8y ago

Is there a good reason why we use separate SSD controllers instead of letting the primary cpu handle it? The obvious reason is backwards compatibility, but as more of computing moves to SSDs, is this still relevant? ZFS has shown that removing layers of abstraction with regard to storage can be beneficial.

pixl97 8y ago
https://azure.microsoft.com/en-us/blog/project-denali-to-define-flexible-ssds-for-cloud-scale-applications/ https://azure.microsoft.com/en-us/blog/project-denali-to-def...
pjc50 8y ago
That adds a round of latency, and makes it pretty much impossible to boot off the drive. The blocks aren't in the same order in the Flash as they are presented by its interface, and one of the main jobs of the controller is to re-order them. It would be an interesting product to have, a raw block API to a Flash device with all the temporary state stored on the host - but a hard one to sell, as it's not differentiated in any way.
- blattimwind 8y ago
  There are host-managed SMR drives, which share a number of characteristics with flash storage.
selectodude 8y ago
Apple uses their T2 security enclave as the SSD controller and it's caused quite a stir.
- joosters 8y ago
  I wonder if you can read any extra state out of the T2 as a result, e.g. more information on wear leveling, temporary read failures and so on, more than the standard SMART counters?