Extremely slow initial blockchain sync (~1% a day)

The initial blockchain download is VERY slow on my setup, like 1% a day. I am on a very fast (500/500 mbps) Internet and connected directly to my router via Ethernet.

Here is my hardware:

  • Raspberry Pi 4 4GB Model B with 1.5GHz 64-bit quad-core CPU (4GB RAM)
  • 32GB Samsung EVO+ Micro SD Card (Class 10)
  • Official power supply
  • 1TB SSD (can’t remember the make/model)

What could be the issue?

I had bitcoin core running on the same setup in Linux before and when I tested the SSD speed it was very fast and well over what other posts said it needed to be. I was able to download the blockchain and run fine, but I blew it away for Umbrel.

Any suggestions are welcome. I have downloaded the logs, but they are at home.


Have you tried disconnecting/reconnecting your ethernet cable ? I saw a video on Youtube the other day from someone with a similar issue, and this seemed to be the solution. Seemed to be something wrong with a connection between the Raspberry Pi and the router.

I tried the network cord removal, I tried the power cord removal, I have stayed logged in as long as I could to watch the sync, but literally, I am watching it sync in the hundredths of a percent. I get its a ton of data (17% and its 89G) but wow is this slow. I have a 100Mb download speed from ATT and speed test it just fine at around 80Mbs.

Why does this not seem to sync when I am not logged into the webpage? shouldn’t it sync as a background process?

I am also using a Raspberry Pi (Gen4) with a 2TB flash drive. Any insight / suggestions?

What is the temperature showing?

On the Raspberry Pi?

with an SSD should be way more faster.
Something is wrong with your drive or USB cable.

Went and bought a new SSD drive and recovered the keys. Its resyncing, but we shall see. Thanks for the guidance. They do need to have some kind of “average rate” calculation for syncing. maybe it should be on transactions per minute sync (because small blocks are quick, large blocks are slower).

For a node the most important part in IBD phase are RAM and disk speed. After that RAM used is going down to a normal levels and also disk, but still continue to have heavy I/O usage on disk, due to validations of blocks, LN gossips, sync, electrs indexing and more tasks for a node.
In a normal way, a RaspPi with 8GB RAM and SSD will sync 50% in quite fast way, even 1-2 days, but after that will slow down, reaching the blocks from 2017 onward that were bigger, so will take more time to validate them. The whole process can take up to 6-10 days sometimes.
With a HDD this initial process is even slower up to 12-15 days.
On a VM ius faster due to virtual more memory that can be assigned.

But remember, patience is the key. This process is slow only in the initial phase.



You were so right. The external drive was the issue. I went and bought a Sandisk extreme - 2 TB.

I am a running a Rasp Pi 4, a 100MB down connection and this SanDisk Extreme now and have pulled in 12 hours what took 2 weeks before. Back to 21% (most I got was to 25% before) and it is cycling the transactions in a pretty steady cadence. So IOPS is key.

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Just found this post, very helpful, maybe you can shine some light on my situation:

got this set-up, RaspPi 4, 8GB RAM, SSD with 500MB/s read/write, increased cache size to 6000MB, yet RAM usage is just around 1GB. However, the only bottleneck I see is my current download speed of 2-3 Mbps. I’m not sure about the math here, but shouldn’t this give you 7-10GB download per hour anyways? It makes barely any progress.

Appreciate some insight (if you’re still in this forum)

Hey @SamHumpy after you updated Cache Size make sure you saved that setting - if your speedtest and download speed is showing 3Mbps download 1GB takes 44 minutes, 3Mbps is on the slower side (8 megabits is one megabyte…) so this is going to take a while.

The best advice I can give is to check the uptime in settings of your Pi 4 to make sure it’s not experiencing any connection drops and you remain connected to 10+ peers to keep syncing, only if you are comfortable doing so you can also toggle on “Connect to all Clearnet Peers over Tor” in advanced settings

Let me know if you have any other questions

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Hey @usernameisJim, appreciate your response. That’s the math I was missing, so it takes about 16-17 days.

The Pi is basically running smoothly and temp. is ok. I don’t see much more than 10 peers at any moment and RAM usage has now slowly increased to 2.7GB, but that does not seem to result in increased performance. So in my case, I suspected the hardware does not limit IBD but solely the speed of my internet connection.

Can you briefly elaborate on your suggestion to “toggle on “Connect to all Clearnet Peers over Tor””. I read somewhere to turn it off in order to avoid slowing down the syncing due to the use of the Tor network. Thank you

Bitcoin Node application by default runs behind Tor so we are limited by the nature of Tor networking- but that option can increase peers you connect to, at the sacrifice of some privacy so that is up to you

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