Comment Re:Why Can't It Just Act As Write-Back Cache? (Score 1) 67
Wait, what? Oh I see - are you proposing to add a fully associative cache in front of the 4GB Flash memory to speed up cache lookups and thus lazily storing writes as well?
I thought you were caching the stored data in a cache. I must admit I kinda glossed over the "fully associative with write-back" bit
I suppose that can work - SLC is great for caching writes on. However, it's a lot more work than simply copying hot reads onto the Flash and caching them there. What you're proposing means a lot of new work on the disk controller, whereas now they simply slapped a caching thing on top of what they had.
However, at http://www.cs.umd.edu/class/sum2003/cmsc311/Notes/Memory/fully.html they explain fully associative caches nicely and add that "The hardware for finding the right slot, then picking the slot if more than one choice is available is rather large, so fully associative caches are not used in practice".
I don't think it really matters how Seagate exactly decides to cache stuff - right now they do read-cache only and it would be nice if they did a write-cache as well. You can do that just fine without using fully associative caches for the addressing.
Doing caching right is just not a trivial thing, especially if you have to do it on a tiny embedded platform.