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Comment by arkensaw | Hacker News Reader

Ok I'm not a physicist but surely long term storage of pictures and emails does not actively generate heat in a data-center?

Encouraging people to log on and delete old pics and emails is only going to create more heat as servers have to spin up access to stuff.

The real culprit of data-center heat usage is surely AI

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Storage on spinning disks does. Storage on ssds does as well but should be much less. Cold backups don't. Now, the idea that people can just delete their cat pictures to meaningful impact cooling in the dcs is just garbage, particularly now when most of the energy used in the dcs goes to gpus

My understanding is that SSDs are in the sub-watt territory when idle. So ironically the act of deleting the email instead of keeping the drive in steady-state will likely use significantly more power.

How often do you think a device is idle in a data center? My guess is not very often if ever.

Often, in a system with a large number of drives where actively-used data and cold data are automatically migrated to active and mostly-idle drives respectively.

Consumer SSDs idle at very low power, but SSDs intended for data centers generally idle at several watts.

If the drives are spinning, they generate heat. The drives spin regardless if they are empty or full. In an array setup in large storage pools, there's no spinning down the drives either. Sadly, there's no countering these suggestions to those making them, as they clearly have no understanding of what they are talking about. They're just trying to make their 15 minutes.

It's one thing if they want to raise awareness of how much water is being used by data centers, but it crosses into absurdity with suggestions like "delete your data from the cloud".

Some of the responses here are assuming that your old emails are sat there, quiescent. A better model might be that they are part of a dataset that is actively scanned, repeatedly, so deleting them makes those scanning processes more efficient.

Exactly what those processes might be is left as an exercise for the reader.

In theory if you delete enough you can power off a server.

In practice the random storage and delayed deletion makes this an absurdly asynchronous event.

In reality the UK just doesn't have that many consumer data centres, they mostly serve business. There's not likely even that much AI compute in the UK (yet).

The actual reason (as said elsewhere is water storage planning).

The only thing I can think of is that emails accumulate that that means more storage must be added at the data centres, requiring more electricity use. This seems trivial compared to AI power demands to me.

Storing pictures and emails in a data center does generate heat, but it is negligible. Also, claims of data center water usage are heavily overstated. Some do, but only during summer months. I assume the reason for the UK’s asinine advice is because of they think there is a link between heat generation and water usage at data centers. While a link does exist, it is not straight forward.

I have only ever toured a data center once, but the one I toured had no water usage by the cooling infrastructure as far as I could tell. However, the facility’s APUE was something like 1.7, which is high. I have read that some facilities with impressively low APUE numbers use water during particularly hot summer days, which is presumably for evaporative cooling. Unfortunately, I have yet to see one of these facilities in person to know the details beyond what has been publicly written.

If it counts for anything, I have hundreds of commits in OpenZFS. I know some things about data centers from a mix of professional contacts since my work is used in them (which is how I got the tour in the first place), and personal interest in the subject, but I am far from an expert on all aspects of how data centers work. Speaking of which, I doubt there is any one person who is an expert on all aspects of how data centers work, since the knowledge is spread across multiple types of experts. A physicist would not be my first choice of expert when asking questions about data centers. A data center technician would be a better person to ask.

Something is always more than nothing

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