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My laptop has a 500GB SSD and I couldn't spare two fifths of it for the blockchain so I plugged in a portable 2.5" HDD, altered the command appropriately and it said:

The blockchain is on a rotating drive: this will be very slow, use an SSD if possible

..but I did it anyhow, it took originally perhaps five days for the whole blockchain. Then after a pause of perhaps three months, it has again taken about two or three days just catch that up.

What exactly is it doing? Clearly not just downloading something and putting it on the drive. My internet connection here is quite fast. The speed at which data is written even onto a rotating HDD is likely orders of magnitude greater than the internet connection.

Can anyone write a high level description of what it is doing whereby the slower read write speed somehow compounds to make it hugely slower.

Well, I haven't tried it yet with a plug in SSD so can't be a hundred percent sure that that is the bottleneck but it seems so. I have never before in my life had anything not work adequately due to hard drive speed. RAM, processors, video cards yes, they have limited things, but this is the first time a drive has limited something.

It seems that transacting in Monero requires specific equipment.

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What exactly is it doing? Clearly not just downloading something and putting it on the drive. ...Can anyone write a high level description of what it is doing whereby the slower read write speed somehow compounds to make it hugely slower.

Syncing (which includes downloading, verifying and storing) the blockchain requires lots of read write operations. Spinning HDDs offer significantly less IOPS than SSDs. This is why there is a warning if you are using a HDD.

With blockchain growth (e.g. as usage increases), the problem "compounds" simply because there is more data to process.

..but I did it anyhow

Which is fine. But unless you keep it synced, every time you use, you'll have a slow catch-up sync.

I have never before in my life had anything not work adequately due to hard drive speed. It seems that transacting in Monero requires specific equipment.

I'm not sure of the point you're trying to make here other than you haven't synced a proof-of-work blockchain (Monero, Bitcoin or something else), before. Monero doesn't require specific hardware, but due to the fact you are trying to sync, store and verify a proof-of-work blockchain of > 100 GB size, your experience will be greatly improved by simply using an SSD. The exact same applies to Bitcoin for what it's worth.

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    Just out of curiosity, why all the disk ops to verify? Can't it just be done in RAM until it's finalized? (maybe a option flag? --RAM)
    – Dave
    Sep 8 '21 at 9:30
  • "why all the disk ops to verify? Can't it just be done in RAM" <- Past txs need reading to verify later blocks. So unless you have enough RAM for the whole blockchain, you're going to need to read from disk during verification.
    – jtgrassie
    Sep 8 '21 at 13:21

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