The NOVA filesystem [LWN.net]

The NOVA filesystem

Posted Aug 5, 2017 18:05 UTC (Sat) by Paf (subscriber, #91811)
In reply to: The NOVA filesystem by Tara_Li
Parent article: The NOVA filesystem

In addition to what Corbet noted, most of the proposed tech sits between flash and true RAM in terms of performance. 10x-1000x slower than RAM, depending on tech and what you're measuring (and whose claims of future performance you believe). One could end up quite sad from expecting truly RAM like performance from some persistent memory solutions.

(The above leaves out battery backed DIMMs, I suppose. But they don't seem like a tech with broad applicability.)

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The NOVA filesystem

Posted Aug 6, 2017 3:03 UTC (Sun) by Cyberax (✭ supporter ✭, #52523) [Link] (3 responses)

The current tech is basically a mock-up of future persistent RAM. It's expected to be within the usual DRAM performance range, if not that durable. It'll certainly be faster than flash.

The NOVA filesystem

Posted Aug 6, 2017 17:54 UTC (Sun) by Paf (subscriber, #91811) [Link] (2 responses)

Really? Is it? Intel's marketing of 3D xpoint (available now) sort of suggests it will be RAM level, but the actual numbers are well off. They're faster than flash, but they live between flash and RAM.

They're claiming they'll be ~0.5 microsecond latency, but current 3D xpoint stuff is more like 5 microseconds. Flash is more like 100 microseconds, DRAM is 5-30 nanoseconds. So another 100x faster than 3D xpoint, 1000x if you use the latencies of what you can buy today.

Those numbers are from memory mostly, but I'm pretty sure they're broadly correct. Maybe there's other tech or I've got the #s off a bit...?

So it creates another (fascinating) stopping point in the storage/memory/cache hierarchy.

The NOVA filesystem

Posted Aug 7, 2017 2:23 UTC (Mon) by Cyberax (✭ supporter ✭, #52523) [Link] (1 responses)

You can not buy 3D xpoint on the open market right now (I tried to buy one), apparently it's sold only to Intel partners under heavy NDAs for evaluation purposes only.

All I was able to find were battery-backed DRAMs with flash for longer-term storage, which is kinda disappointing.

The NOVA filesystem

Posted Aug 7, 2017 12:52 UTC (Mon) by Paf (subscriber, #91811) [Link]

Ah, sorry. I'm drawing my info from public sources, and I thought the reviews meant it was generally available.

That IS disappointing.