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Modern SSDs have incredibly large caches. For example, HP EX920, which is a TLC (triple layer cell) SSD, in its 1TB model contains a whooping 200GB of SLC (sing
by yzmtf2008 8y ago
Modern SSDs have incredibly large caches. For example, HP EX920, which is a TLC (triple layer cell) SSD, in its 1TB model contains a whooping 200GB of SLC (single layer cell) cache. It's entirely possible that your changes are simply in cache only, and hasn't been committed to the actual storage.
- undersuit 8y agoI don't know if I'm getting exactly what you're saying, but a sudden power off isn't going to wipe your SSD's SLC cache like it would do the DRAM cache on more expensive drives.
- nightfly 8y agoBut if the controller gets into a weird state and "forgets" to flush the cache and then doesn't even look at the SLC cache on the next boot...
- undersuit 8y agoThe SLC cache is managed by the controller, it's not going to forget to write it to the flash cells being managed as TLC/QLC, the controller is transparently storing your data in both. The controller knows if put some data in the SLC cache and some data in the QLC, and that that data needs to move from SLC to QLC, and that that other data in the SLC was marked deleted so now it can return that entire block to being addressed as QLC. I don't know. I'm just trying to say that since flash isn't volatile the SLC cache isn't treated as volatile cache either.
- ptman 8y agoIt's probably more like the superblock not being updated to point to the newest data. Instead it points to old data that hasn't been garbage collected.