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Comment by dangrossman | Hacker News Reader

I can't wait for the DigitalOcean of RAM to appear. $5/mo VPS with 20GB RAMdisks, please.

Anandtech had a nice recent article on server memory types and costs: http://www.anandtech.com/show/7479/server-buying-decisions-m... (https://news.ycombinator.com/item?id=7044992). It prompted me to go through and do some math.

If you want to cram as much RAM in a server as practical, you'll currently be using 32GB LRDIMM's which currently cost ~$600 ($20/GB). Some dual-processor motherboards will take 24 of them (3 ranks * 4 channels * 2 processors) for a 768 GB total: http://www.supermicro.com/products/motherboard/xeon/c600/x9d...

(The 1.5TB description for the board presumes the soon to be released 64GB LRDIMMS.)

This would be $15000 for just the 768GB of RAM. Let's guess another $5K for the rest, so $20K for the machine. At 20GB of dedicated RAM per VPS, you can fit ~40 of them on the machine. $20K / 40 = $500. Since this ignores power and connectivity, I think you'll be waiting a while for a $5 month plan. Although perhaps you could overprovision and swap out a lot?

Viewed alternatively, the sweet spot for selling RAM does not involve putting as much of it as you can in a single machine. You'd cut the cost of your RAM per GB a lot (down to about $10/GB) if you stuck with older lower density RAM put a bunch of low price blade servers in a single box.

Space in a datacenter gets prohibitively expensive fast.

You'd need a real nifty virtualization platform to oversell RAM like we currently oversell bandwidth and cpu time.

A high performance swap farm might be the way to go with things, but things break when everyone starts using huge pages.

Right, the trouble with RAM is that if someone wants to keep a pile of data in memory, it has to stay loaded. I would hazard a guess that memory consumption on servers tends to be much less spiky than CPU is, and that's part of why a "DigitalOcean of RAM" is difficult to do.

Did you use bulk pricing in your calculations? Hosting services that buy in bulk would have a lot of bargaining power.

I did not. I'd be interested to know what the wholesale prices are for 32GB LRDIMM's. My instinct is that there wouldn't be much of a discount until you are buying entire production runs, but this isn't an area I know about.

It could be very interesting for VMs with transient storage that need fast IO, but don't need to persist it on the machine itself. Thinking stream consolidation or analysis.

Session database in memory, mirrored to another host for redundancy, and only events that need to be stored written to "slow" SSDs when I/O bandwidth permits.

I could bring my startup from 10 to 2 hosts and have better performance.

To be fair, that should be doable right now with DDR3. It's still much faster than an SSD.

I suppose that's true, thanks for putting that in perspective.

The real problem is that gobs of RAM isn't _cheap_. I wish that DDR4 would make DDR3 less expensive, but as manufacturers switch to making DDR4, I expect the price to rise.

edit: Which is to say, I'd be happy if it became possible in the near future to get laptops with 48GB of of DD3 and junky Dell rackmounts with 256GB of RAM for today's prices of 16/64GB respectively.

> Which is to say, I'd be happy if it became possible in the near future to get laptops with 48GB of of DD3

The reason laptops still come with just 4GB of RAM has little to do with the cost of RAM. Each gig you add reduces battery life significantly.

There are also diminishing returns for the average user. My mother would notice an SSD, but probably not another 4 gigabytes of RAM. Her computer almost never hits the swap partition.

My last several laptops (System76) came with 16GB. Though I have never looked at the impact to battery...

I run multiple VMs on my machine continuously (a win7 VM and a couple other linux VMs). The machine has dual SSDs and it's super freaking fast.

That's quite common. Redis etc.

redis is key/value, not meaning to be full normalized database

Redis has complex data structures, not just key/val. You can also run a SQL db in-memory anyway.

it's still k/v, it's just the values can be several different types of DS

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