Bitcoin core slow sync/download of the blockchain

[canudinho]

Hello everyone

Gonna be fast...

I'm trying to download the Blockchain (by btc core) on an external HD, using my laptop (256 ssd, 8gb RAM). My internet connection is around 300mbps, and it is doing great, but the same way it keeps downloading 0,03% per hour... What can I do for optimizing this process ?? Just gotta download this and it won't work this by this speed.

Best regards

[BitMaxz]

Let me ask if your external drive is HDD or SSD?
if all Bitcoin core data is in HDD then that might be the bottleneck.
You can try to add dbcache under the bitcoin.conf file and set it to half of your total ram memory or just 3000mb.

Code:

dbcache=4096

Or you can try splitting the data by manually adding datadir on bitcoin.conf file for the SSD and then blocksdir into your external drive.

Check the reference below for a solution
- https://github.com/bitcoin/bitcoin/issues/14595

[NeuroticFish]

I've written this before, but I don't have now the patience to look it up, however, there are plenty of tutorials for this:

If you want faster initial sync, it's not only the dbcache, CPU, internat speed that are of help. You can make use of your SSD too.
Yes, since it's a small SSD you can't store the blockchain there, but you can store the chainstate there (7.6 GB now) and if you use indexes then those too (indexes = 43.5 GB, but you probably don't want txindex).

I've used symlinks for the job, but maybe there are other options too. And yes, after initial sync has ended I've moved the data from SSD to HDD onto the correct locations.

[nc50lc]

My internet connection is around 300mbps, and it is doing great, but the same way it keeps downloading 0,03% per hour... What can I do for optimizing this process ?? Just gotta download this and it won't work this by this speed.

Don't worry too much about that displayed 0.03% per hour rate, it tends to underestimate a lot.
For reference, when I'm catching up my node to the tip with about 7 days worth of blocks to download, it'll show me that it would take 2 days to sync at a rate that's close to yours,
but in reality, it always only takes less than an hour to finish.

But aside from that, your setup is really getting a bottleneck with that external hard drive as others have mentioned.
Follow their suggestion if you want faster sync speed.

You may also want to check if you're connected to enough peers to download the blockchain from since in some cases, nodes cannot connect to others.

[LoyceV]

Code:

dbcache=4096

Is that even enough? Considering the size of chainstate, I'd say 8192 MB dbcache is better, but OP doesn't have enough RAM for that.

Don't worry too much about that displayed 0.03% per hour rate, it tends to underestimate a lot.

My experience is the opposite when I start from scratch: the rate is quite uptimistic for the first hours, but becomes slower  once it reaches more recent years of data.

@OP: syncing Bitcoin Core is more than just downloading the blockchain. It includes verifying every Bitcoin transaction ever made, which is very demanding for your hardware. An external drive is far from ideal, and it's risky. If you ever accidentally unplug it, you risk corrupting your data.
My advice: decide what you need first. You've also opened a topic about Electrum, which works great on your hardware. Or prune the blockchain if you don't have a specific reason to keep all data, so it fits on your internal SSD.

[nc50lc]

Don't worry too much about that displayed 0.03% per hour rate, it tends to underestimate a lot.

My experience is the opposite when I start from scratch: the rate is quite uptimistic for the first hours, but becomes slower  once it reaches more recent years of data.

That's normal for the older nearly empty blocks where there's little to no data to verify.
If he's getting that 0.03% per hour estimate at that part, the issue could be something more than just the hardware bottleneck.

[DaveF]

1)  What CPU?
2) USB 3 or 2 on the external drive.

What others have discussed is true but running an older Celeron and an old spinning external drive on USB 2 is going to be a totally different experience then an 6th gen i5 and a newer 7200RPM external on USB3

-Dave

[DaveF]

Another side note, not related to the OP since they are on a USB device.
But for internal drives, I am really starting to see BIG differences between the top of the line SSD / NVMe and the cheap generic ones.

There was always a performance difference, but the spread of performance seems to be getting larger.
If you are just running core on the machine and noting else it's not a real concern once the IBD is done.

But with a full LN node, and a few other things the generic I have is the bottleneck. The exact same spec hardware with a Samsung is not having the same slowdown.
However....the Samsung was probably 50% more expensive so there is that....

-Dave

[philipma1957]

you can get away with a sata ssd 2tb 8gb ram and an i5 third gen laptop.

I have  a 2tb crucial running linux mint on an asus third gen i5 (let me check )

could be  an i7 third gen.

This was a toss away laptop cost free. ssd was 85 bucks.

I downloaded the entire oct 2023 chain in 22 hours . my net speed is 200 max via optimum.

https://bitcointalk.org/index.php?topic=5468600.0

here is the thread.

it was a third gen i7 laptop 💻

[satscraper]

@ OP, if sync is still an issue then add to bitcoin.conf file the following entries:

dbcache=<M>

# where   M equals to 1/4 RAM, for instance if you RAM = 8Gb then dbcache=2048

blocksonly=1

# this will increase the sync  speed as it  disables node listening and "stop requesting and relaying transactions unless they are part of the block". After full initial sync you may remove this  entry.

[apogio]

Hello everyone

Gonna be fast...

I'm trying to download the Blockchain (by btc core) on an external HD, using my laptop (256 ssd, 8gb RAM). My internet connection is around 300mbps, and it is doing great, but the same way it keeps downloading 0,03% per hour... What can I do for optimizing this process ?? Just gotta download this and it won't work this by this speed.

Best regards

Hi mate.

The fastest way since you have an SSD in your machine is to copy the Chainstate directory and the Indexes directory to your SSD and create a symlink to look at those directories.

Here is a video with instructions. I saw a huge difference when I followed those steps:

https://youtu.be/q3zY9BbyfEU?si=DaRyT0cXRD7QbPzc

Keep in mind to copy the directories back to the original location when you are done with IBD. Also remove the symlinks.

If you need further assistance, let me know.