3 ms·

Sadly the solution, a firmware variant with ZNS instead of the normal random write block device, just isn't on offer (please tell if I'm wrong; I'd love one!).

by namibj 3y ago

Sadly the solution, a firmware variant with ZNS instead of the normal random write block device, just isn't on offer (please tell if I'm wrong; I'd love one!). Because with ZNS you can get away with tiny caps, large enough to complete the in-flight blocks (not the buffered ones, just those that are already at the flash chip itself), plus one metadata journal/ring buffer page to store write pointers and zone status for all zones touched since the last metadata write happened. Given that this should take about 100 μs, I don't see unannounced power loss really that problematic to deal with. In theory the ATX PSU reports imminent power loss with a mandatory notice of no less than 1ms; this would easily be enough to finish in-flight writes and record the zone state.

jauntywundrkind 3y ago
It's fucking wild to me the trajectory here: OpenChannelIO: stop making such absurd totalizing systems that hide the actual flash! We don't need your fancy controllers! Just give us a bunch of flash that we can individually talk to & control ourselves from the host! You leave so much performance on the table! There's so many access patterns that wouldn't suck & would involve random rewrites of blocks! Then after years of squabbling, eventually: ok we have negotiated for years. We will build new standards to allow these better access patterns that require nearly no drive controller intermediation, that have exponentially higher degrees of mechanistic sympathy of what flash actually does. Then we will never release drives mainstream & only have some hard to get unbelievably expensive enterprise drives that support it. You are so f-ing spot on. This ZNS would be perfect for lower reliability consumer drives. But: market segmentation. The situation is so fucked. We are so impeded from excelling, as a civilization, case number nine billion three hundred forty two.

by namibj 3y ago

jauntywundrkind 3y ago

It's fucking wild to me the trajectory here: OpenChannelIO: stop making such absurd totalizing systems that hide the actual flash! We don't need your fancy controllers! Just give us a bunch of flash that we can individually talk to & control ourselves from the host! You leave so much performance on the table! There's so many access patterns that wouldn't suck & would involve random rewrites of blocks! Then after years of squabbling, eventually: ok we have negotiated for years. We will build new standards to allow these better access patterns that require nearly no drive controller intermediation, that have exponentially higher degrees of mechanistic sympathy of what flash actually does. Then we will never release drives mainstream & only have some hard to get unbelievably expensive enterprise drives that support it. You are so f-ing spot on. This ZNS would be perfect for lower reliability consumer drives. But: market segmentation. The situation is so fucked. We are so impeded from excelling, as a civilization, case number nine billion three hundred forty two.