400 ns access latency? Why so high? Is high latency the cost of the high density or is the extra latency due to Gen-Z protocol's high overhead? The 30 GB/s of bandwidth is also rather low. Is the "30" number a typo? That 400 Gbps of total bandwidth mentioned above is equivalent to 50 GB/s of bandwidth, not 30 GB/s. Is there a protocol limit to how many of these modules can be used at the same time or is the limit imposed by the available slots of the server motherboard?
High for DRAM but the deterministic aspect is interesting. This provides reliable bounds for access times. Knowing when the data arrives before it does permits optimizations for things like context switching in a pre-emptive manner while minimizing idle time. So while the raw performance may not be that great it does provide mechanisms to be efficient.
Bandwidth-wise: the way I read it: - the _controller_ supports up to 400 Gbps total bandwidth - the _specific configuration_ for this particular device (using that controller) offers 30 GB/s
In other words, the controller is capable of more performance, in theory - but isn't being maxed out in this specific design.
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azfacea - Thursday, August 15, 2019 - link
wtf ? ddr4 ? edsff ? "gen-z lanes"p1esk - Thursday, August 15, 2019 - link
EDSFF: Enterprise and Datacenter SSD Form Factor https://www.anandtech.com/show/13218/ssd-form-fact...Gen-Z: new interconnect standard https://genzconsortium.org/about-us/gen-z-technolo...
DDR4: really?
azfacea - Thursday, August 15, 2019 - link
i know about EDSFF and DDR4. i meant what the fuck is ddr4 doing in EDSFFDanNeely - Thursday, August 15, 2019 - link
ramdisk?CheapSushi - Tuesday, August 20, 2019 - link
The vast majority of drives have DRAM on them...Santoval - Thursday, August 15, 2019 - link
400 ns access latency? Why so high? Is high latency the cost of the high density or is the extra latency due to Gen-Z protocol's high overhead? The 30 GB/s of bandwidth is also rather low. Is the "30" number a typo? That 400 Gbps of total bandwidth mentioned above is equivalent to 50 GB/s of bandwidth, not 30 GB/s. Is there a protocol limit to how many of these modules can be used at the same time or is the limit imposed by the available slots of the server motherboard?CaedenV - Thursday, August 15, 2019 - link
is .4ms considered 'high latency' for storage these days? Still seems faster than most SSDs on the marketEmotiveElectron - Thursday, August 15, 2019 - link
It's not 0.4ms.400ns is 0.0004ms (0.4us). Plus this is roundtrip latency. So 200ns each direction. Actually impressively fast!
p1esk - Friday, August 16, 2019 - link
This is DRAM, not flash. 400ns is pretty slow for DRAM.Kevin G - Monday, August 19, 2019 - link
High for DRAM but the deterministic aspect is interesting. This provides reliable bounds for access times. Knowing when the data arrives before it does permits optimizations for things like context switching in a pre-emptive manner while minimizing idle time. So while the raw performance may not be that great it does provide mechanisms to be efficient.boeush - Thursday, August 15, 2019 - link
Bandwidth-wise: the way I read it:- the _controller_ supports up to 400 Gbps total bandwidth
- the _specific configuration_ for this particular device (using that controller) offers 30 GB/s
In other words, the controller is capable of more performance, in theory - but isn't being maxed out in this specific design.
QChronoD - Friday, August 16, 2019 - link
30GB/s = 320Gbps, 80% of the 400Gbps of the controller.Vatharian - Saturday, August 17, 2019 - link
30GB/s = 240 Gb/s, or you know something I don't.ats - Thursday, August 15, 2019 - link
Because it is in effect being accessed across a ethernet interface. And once you add in the required switches, it will easily be over 1000ns, fyi.name99 - Friday, August 16, 2019 - link
So this is basically competition for Optane DIMMs? Same sort of space?If so, how does it compare?