Re:How “latency numbers everybody should know” decreased fro...
by Dylan16807 on Thursday March 03, 2022 @10:25PM
(#30550329)
Even the 2012 data is suspect.
"Seek + rotational delay halves every 10 years" just isn't true. We got rid of the >7200 drives and are basically sitting still on that metric. And hard drives weren't at 400MB/s in 2012 either. (The disk bandwidth section also cites a 2012 presentation with correct numbers, but something went wrong in translation.)
Re:How “latency numbers everybody should know” decreased fro...
by marcan_42 on Friday March 04, 2022 @02:46AM
(#30551830)
Yeah, I was wondering where the heck 2ms disk seek times came from. That's not a thing and will never be a thing; disks only spin so fast, and nobody even uses >7200RPM drives any more (because we've all moved to SSDs instead).
Re:How “latency numbers everybody should know” decreased fro...
by bufferoverflow on Friday March 04, 2022 @04:26AM
(#30552457)
Oh 7200 drives are used. Mainly for large data storage. If you deal with high quality videos (RAW 4K or 8K), SSDs are way too expensive to store them.
Re:How “latency numbers everybody should know” decreased fro...
by mjochim on Friday March 04, 2022 @04:41AM
(#30552557)
GP was likely refering to extraordinary disks with more than 7200 rpm
Re:How “latency numbers everybody should know” decreased fro...
by thisisnico on Friday March 04, 2022 @11:10AM
(#30556655)
10KRPM SAS drives in my SAN.
Re:How “latency numbers everybody should know” decreased fro...
by quietbritishjim on Friday March 04, 2022 @04:40AM
(#30552554)
The parent comment said no one uses drives strictly faster than 7200.
Re:How “latency numbers everybody should know” decreased fro...
by bufferoverflow on Friday March 04, 2022 @05:02AM
(#30552680)
Pretty sure 10K RPM drives are used too.
Re:How “latency numbers everybody should know” decreased fro...
by vidarh on Friday March 04, 2022 @05:10AM
(#30552748)
They're used, but rare because they got to a weird position in between slower drives that are cheaper to produce and operate and SSDs. E.g. 15K RPM drives were a thing but while you can still buy some models they're typically more expensive than SSDs, so you mostly buy them to replace drives in existing arrays.
Re:How “latency numbers everybody should know” decreased fro...
by quietbritishjim on Friday March 04, 2022 @05:05AM
(#30552705)
I have no opinion on the matter, just pointing out that your comment doesn't follow from the previous one. But I imagine that when they said "nobody" uses faster disks, they were exaggerating a bit. The question is whether the default set of "latency numbers everyone should know" should reference SSDs or uncommon spinning disks.
Re:How “latency numbers everybody should know” decreased fro...
by ChuckMcM on Thursday March 03, 2022 @11:56PM
(#30550855)
Looks like a fun project to bring it up to date.
Re:How “latency numbers everybody should know” decreased fro...
by gurjeet on Friday March 04, 2022 @12:35AM
(#30551059)
Where would one lookup such data, if one is interested in updating the code.
Re:How “latency numbers everybody should know” decreased fro...
by ChuckMcM on Friday March 04, 2022 @12:41AM
(#30551094)
I would start by going through the Anandtech reviews of the major processor and storage announcements. They generally do a great job of benchmarking and go into pretty good detail. Datasheets from manufacturers would also be useful although not all data is routinely provided.
The code was written back in 2012 and is using numbers from back then to _guess_ what future numbers would look like!
(I was fooled by it too)
See https://github.com/colin-scott/interactive_latencies/issues/...