Samsung's 970 EVO SSDs Reviewed – 500GB and 1TB

Re:Samsung's 970 EVO SSDs Reviewed – 500GB and 1TB by nine_k on Tuesday April 24, 2018 @02:45PM (#16915433)

This makes sense! OTOH low-drop diodes do exist [1], and the drive likely needs just a (small) fraction of a second to flush the caches; it's SSD, not need to wait for the disk to rotate to the right position or move heads. I suppose the power loss signal from the controller still propagates, even if the computer's PSU plug is just yanked out of socket.

[1]: https://electronics.stackexchange.com/a/282471/9909

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Re:Samsung's 970 EVO SSDs Reviewed – 500GB and 1TB by londons_explore on Wednesday April 25, 2018 @08:54AM (#16921050)

The caches on some SSD's can be multiple gigabytes.

They also frequently cache data which can be difficult (slow) to write, for example a single modified 4kb page which is part of a large unmodified area. Completing that write would involve reading the original data, erasing the entire erase-block, and rewriting the new data.

SSD's with built in power loss prevention typically reserve an area on the SSD which is pre-erased ready to dump the contents of the cache into. Then on powerup, they reload the cache and properly flush the data to the actual place it's supposed to be.

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Re:Samsung's 970 EVO SSDs Reviewed – 500GB and 1TB by jotux on Tuesday April 24, 2018 @02:49PM (#16915467)

I implemented a power-loss circuit on a custom USB memory device (battery-backed LPDDR disks) and used something similar: the MAX40200[1].

[1]https://www.maximintegrated.com/en/products/analog/amplifier...

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