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Comment by stupidcar | Hacker News Reader

It seems like the article maybe misrepresents what the thesis that inspired it says[1]. From the abstract:

"... the device still has its freedom to control block-allocation decisions, enabling it to execute critical tasks such as garbage collection and wear leveling ... Next, we present Nameless Writes, a new device interface that removes the need for indirection in flash-based SSDs. Nameless writes allow the device to choose the location of a write; only then is the client informed of the name (i.e., address) where the block now resides."

So it sounds like this approach is actually removing responsibility from the filesystem, not the firmware.

[1] http://research.cs.wisc.edu/adsl/Publications/yiying-thesis1...

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I have now read the thesis lightly, and I cannot for the life of my children, find out exactly WHY you want to save the simplest of abstractions on the device, namely the logical to physical translation. It's a well known abstraction, and the benefits are clear as day - the alternative, with migration callback and now two different kinds of data that you must write differently just screams bad idea, and goes against everything I've learned in CS and in my carreer. It introduces unneeded complexity for the OS. The main benefit seems to be lower cost devices (1GiB ram per 1TiB), which is neglectable. The performance isn't really better and the thesis doesn't exactly go into detail of the CPU overhead of this implementation during heavy IO, and we now face an entirely different problem with crashes. Today we can build SSDs to ensure that confirmed writes are guranteed persisted.

This abstractions is what have allowed us to transistion from a traditional spinning data store to SSD without much effort (save for delete flags to help the device performance GC and improve performance).

Nameless writes save an indirection layer -- but quite a cheap one!

They add significant latency to write operations, though, which is a high price to pay for such a small gain.

SSDs are so fast let's make them slow again!

Indeed; it sounds like it's creating a clean abstraction layer for the kinds of time-space guarantees flash memory wants to give, where what we have now is very muddled due to being based on the kinds of time-space guarantees spinning media (or even tape drives) wanted to give.

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