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SSDs have become fast, except in the cloud

(databasearchitects.blogspot.com)
589 points greghn | 11 comments | 20 Feb 24 16:59 UTC | HN request time: 2.146s | source | bottom
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pclmulqdq ◴[20 Feb 24 17:22 UTC] No.39443994[source]▶
This was a huge technical problem I worked on at Google, and is sort of fundamental to a cloud. I believe this is actually a big deal that drives peoples' technology directions.

SSDs in the cloud are attached over a network, and fundamentally have to be. The problem is that this network is so large and slow that it can't give you anywhere near the performance of a local SSD. This wasn't a problem for hard drives, which was the backing technology when a lot of these network attached storage systems were invented, because they are fundamentally slow compared to networks, but it is a problem for SSD.

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jsnell ◴[20 Feb 24 17:31 UTC] No.39444096[source]▶
According to the submitted article, the numbers are from AWS instance types where the SSD is "physically attached" to the host, not about SSD-backed NAS solutions.

Also, the article isn't just about SSDs being no faster than a network. It's about SSDs being two orders of magnitude slower than datacenter networks.

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pclmulqdq ◴[20 Feb 24 17:35 UTC] No.39444161[source]▶
It's because the "local" SSDs are not actually physically attached and there's a network protocol in the way.
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yolovoe ◴[20 Feb 24 20:51 UTC] No.39446742[source]▶
You’re wrong. Instance local means SSD is physically attached to the droplet and is inside the server chassis, connected via PCIe.

Sourece: I work on nitro cards.

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tptacek ◴[20 Feb 24 21:32 UTC] No.39447200[source]▶
"Attached to the droplet"?
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sargun ◴[20 Feb 24 22:25 UTC] No.39447821[source]▶
Droplets are what EC2 calls their hosts. Confusing? I know.
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tptacek ◴[20 Feb 24 22:26 UTC] No.39447828[source]▶
Yes! That is confusing! Tell them to stop it!
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1. kiwijamo ◴[21 Feb 24 00:57 UTC] No.39448983[source]▶
FYI it's not a AWS term, it's a DigitalOcean term.
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2. tptacek ◴[21 Feb 24 01:10 UTC] No.39449067[source]▶
I could not be more confused. Does EC2 quietly call their hosting machines "droplets"? I knew "droplets" to be a DigitalOcean team, but DigitalOcean doesn't have Nitro cards.
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3. apitman ◴[21 Feb 24 01:33 UTC] No.39449214[source]▶
Now I'm wondering if that's where DO got the name in the first place
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4. sargun ◴[21 Feb 24 02:03 UTC] No.39449367[source]▶
I believe AWS was calling them droplets prior to digital ocean.
5. chatmasta ◴[21 Feb 24 02:50 UTC] No.39449620{3}[source]▶
Surely "droplet" is a derivative of "ocean?"
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6. arrakeenrevived ◴[21 Feb 24 03:35 UTC] No.39449858{4}[source]▶
Clouds (like, the big fluffy things in the sky) are made up of many droplets of liquid. Using "droplet" to refer to the things that make up cloud computing is a pretty natural nickname for any cloud provider, not just DO. I do imagine that DO uses "droplet" as a public product branding because it works well with their "Ocean" brand, though.

...now I'm actually interested in knowing if "droplet" is derived from "ocean", or if "Digital Ocean" was derived from having many droplets (which was derived from cloud). Maybe neither.

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7. ◴[21 Feb 24 03:45 UTC] No.39449914[source]▶
8. driftnet ◴[21 Feb 24 15:32 UTC] No.39455023{5}[source]▶
Clouds are water vapor, not droplets.
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9. abadpoli ◴[21 Feb 24 15:55 UTC] No.39455368{6}[source]▶
“Cloud: Visible mass of liquid droplets or frozen crystals suspended in the atmosphere“

https://en.wikipedia.org/wiki/Cloud

10. yolovoe ◴[22 Feb 24 02:25 UTC] No.39462407[source]▶
It’s an internal ec2 term too. We don’t use it externally and I shouldn’t have used it to avoid all this confusion.

Internally, we say droplet instead of host as there are multiple hosts/mobos per droplet these days. It’s no longer true that when you get a metal droplet, you get the entire droplet.

11. singleshot_ ◴[27 Feb 24 00:23 UTC] No.39518545{6}[source]▶
Clouds are condensed water droplets in the air. The air below the cloud has just about the same amount of water in it, but at the altitude of the bottom of the cloud, the atmosphere is cool enough for that water vapor to condense, forming the cloud.

Search terms include “lapse rate” if you would like to learn more.