SSDs have become fast, except in the cloud • Hacker News Board

Re: SSDs have become fast, except in the cloud

#31

Post by [deleted] » Tue, Feb 20, 2024, 5:32 PM UTC

ejb999 wrote: post #19

pclmulqdq wrote: post #11

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, whi…

How much faster would the network need to get, in order to meet (or at least approach) the speed of a local SSD? are we talking about needing to 2x or 3x the speed, or by factors of hundreds or thousands?

[deleted]

Re: SSDs have become fast, except in the cloud

#32

Post by Filligree » Tue, Feb 20, 2024, 5:32 PM UTC

ejb999 wrote: post #19

pclmulqdq wrote: post #11

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, whi…

How much faster would the network need to get, in order to meet (or at least approach) the speed of a local SSD? are we talking about needing to 2x or 3x the speed, or by factors of hundreds or thousands?

The Samsung 990 in my desktop provides ~3.5 GB/s streaming reads, ~2 GB/s 4k random-access reads, all at a latency measured at around 20-30 microseconds. My exact numbers might be a little off, but that's the ballpark you're looking at, and a 990 is a relatively cheap device.

10GbE is about the best you can hope for from a local network these days, but that's 1/5th the bandwidth and many times the latency. 100GbE would work, except the latency would still mean any read dependencies would be far slower than local storage, and I'm not sure there's much to be done about that; at these speeds the physical distance matters.

In practice I'm having to architecture the entire system around the SSD just to not bottleneck it. So far ext4 is the only filesystem that even gets close to the SSD's limits, which is a bit of a pity.

Re: SSDs have become fast, except in the cloud

#33

Post by fngjdflmdflg » Tue, Feb 20, 2024, 5:32 PM UTC

pclmulqdq wrote: post #11

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, whi…

So do cloud vendors simply not use fast SSDs? If so I would expect the SSD manufacturers themselves to work on this problem. Perhaps they already are.

Re: SSDs have become fast, except in the cloud

#34

Post by adastra22 » Tue, Feb 20, 2024, 5:33 PM UTC

nullindividual wrote: post #10

ThrowawayTestr wrote: post #5

Earlier quoted context omitted.

Buy a server

I don't like this answer. When I look at cloud, I get to think "finally! No more hardware to manage. No OS to manage". It's the best thing about the cloud, provided your workload is amenable to PaaS. It's great because I don't have to manage Windows or IIS. Microsoft does that part for me and significantly cheaper than it would be to employ me to do that work.

There is tooling to provide the same PaaS interface though, so your cost doing those things amounts to running OS updates.

Re: SSDs have become fast, except in the cloud

#35

Post by SteveNuts » Tue, Feb 20, 2024, 5:33 PM UTC

vlovich123 wrote: post #14

pclmulqdq wrote: post #11

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, whi…

Why do they fundamentally need to be network attached storage instead of local to the VM?

Because even if you can squeeze 100TB or more of SSD/NVMe in a server, and there are 10 tenants using the machine, you're limited to 10TB as a hard ceiling.

What happens when one tenant needs 200TB attached to a server?

Cloud providers are starting to offer local SSD/NVMe, but you're renting the entire machine, and you're still limited to exactly what's installed in that server.

Re: SSDs have become fast, except in the cloud

#36

Post by catherinecodes » Tue, Feb 20, 2024, 5:33 PM UTC

teaearlgraycold wrote: post #2

What’s a good small cloud competitor to AWS? For teams that just need two AZs to get HA and your standard stuff like VMs, k8s, etc.

Hetzner and Entrywan are pure-play cloud companies with good prices and support. Hetzner is based in Germany and Entrywan in the US.

Re: SSDs have become fast, except in the cloud

#37

Post by wmf » Tue, Feb 20, 2024, 5:33 PM UTC

ejb999 wrote: post #19

pclmulqdq wrote: post #11

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, whi…

How much faster would the network need to get, in order to meet (or at least approach) the speed of a local SSD? are we talking about needing to 2x or 3x the speed, or by factors of hundreds or thousands?

Around 4x-10x depending on how many SSDs you want. A single SSD is around the speed of a 100 Gbps Ethernet link.

Re: SSDs have become fast, except in the cloud

#38

Post by adrr » Tue, Feb 20, 2024, 5:33 PM UTC

pclmulqdq wrote: post #11

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, whi…

If the local drives are network drives(eg: SAN) then why are they ephemeral?

Re: SSDs have become fast, except in the cloud

#39

Post by bugbuddy » Tue, Feb 20, 2024, 5:34 PM UTC

mkoubaa wrote: post #25

pclmulqdq wrote: post #11

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, whi…

Dumb question. Why does the network have to be slow? If the SSDs are two feet away from the motherboard and there's an optical connection to it, shouldn't it be fast? Are data centers putting SSDs super far away from motherboards?

> One theory is that EC2 intentionally caps the write speed at 1 GB/s to avoid frequent device failure, given the total number of writes per SSD is limited.

This is the theory that I would bet on because it lines up with their bottom line.

Re: SSDs have become fast, except in the cloud

#40

Post by formercoder » Tue, Feb 20, 2024, 5:34 PM UTC

mkoubaa wrote: post #25

pclmulqdq wrote: post #11

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, whi…

Dumb question. Why does the network have to be slow? If the SSDs are two feet away from the motherboard and there's an optical connection to it, shouldn't it be fast? Are data centers putting SSDs super far away from motherboards?

What happens when your vm is live migrated 1000 feet away or to a different zone?