Cannot catch up with the blockchain - block download too slow

[JackH]

After multiple restarts, I have come to realize my Bitcoin-Qt wont be able to catch up with the rest of the network. The download of each block is slower than block creation, and there seems to be no way of optimizing this by simply logging into Bitcoin-Qt and hoping to reach peers that actually propagates the blocks fast enough. It seems as if there are too many "rotten peers" out there.

My specs on this computer have always been the same, the problem is actually something that has struck me recently. In the past I had no problem downloading blocks in only a matter of minutes and thus re-synch back with the network. Now I wont ever reach it as it currently stands. I am using the latest Bitcoin-Qt and obviously I have checked the tutorials and articles about computer specs.

If anyone has any idea at this point, I am all for it.

[grifferz]

Use a wallet that uses Simplified Payment Verification to avoid keeping a local copy of the blockchain, such as Electrum?

https://electrum.org/

[JackH]

Yeah that is a sad solution. Thats like telling users of Bitcoin to not participate in Bitcoin any longer as nodes. This is not an option for me, I want to run Qt and figure out why this behaviour is occurring.

[grifferz]

Satoshi never expected that every user would run a full node, so this isn't a sad solution but in fact the norm should bitcoin ever approach the mainstream.

I'm assuming you actually have the bandwidth to download the blocks in time, so is the problem CPU usage?

[JackH]

It is definitely not a hardware problem, since these are my specs:

Memory: 5.7 GiB
Processor: Intel® Core™ i3-2330M CPU @ 2.20GHz × 4
Available disk space: 375.5 GiB
Bandwidth is more than enough. I can do 10 youtube videos at the same time. I assume that should be enough for block downloads.

I am running Ubuntu 12.04 on my laptop.

As I said, I never had a problem syncing up to the network, before this week, after I had not logged onto the network for 2 weeks. All the sudden my block download is 1 block every 10 min or less. I am actually falling behind the network as time goes by. I am either extremely unlucky and keep hitting bad peers, corrupted peers or something is wrong somewhere else. I would like to understand where the problem is, as I think this would benefit people insisting on running Qt as I do.

[GoldenWings91]

Syncing to the network after a nights sleep usually took me a half hour to an hour. I didn't think much of it since I run my node behind tor and thought tor is the bottleneck. Then I bought an ssd and now syncing to the network takes about two minutes   while still behind tor. Are you sure your hard drive isn't the bottleneck?

If you want to test whether the problem is in your end I can pm you the ip of my node you can then connect to it directly, I have 5MB uplink and am not throttling anything.

Code:

-connect=<ip>

[piotr_n]

After multiple restarts, I have come to realize my Bitcoin-Qt wont be able to catch up with the rest of the network. The download of each block is slower than block creation.

Unlikely.

Even if you assume that all the blocks have the maximum size you would need to have a bandwidth lower than 16kbps (meaning bits, not bytes) to have a download of each block slower than block creation.

More likely is that your PC is just too slow - it doesn't catch up with verifying the blocks quickly enough and flushing them to the disk.

[JackH]

If anything, I can blame the network itself and not the computer. I will report back after I try this on another WiFi to at least pinpoint the problem to either computer or network.

[piotr_n]

Well, it is possible that you are routing too many transactions which increases the traffic.

But the downloading of the blocks itself should only take max ~14kbps.
And with the current average block size, even like 4-5 times less.

[JackH]

I am actually afraid my problem is something completely different. I think I am affected by this: http://arstechnica.com/security/2014/02/dear-asus-router-user-youve-been-pwned-thanks-to-easily-exploited-flaw/

For some reason, pre installing the upgrade, it was running like this yesterday (slow). After upgrade, it raw flawless. Then I noticed that some dude on the Ars comments pointed to this (the last comment in the Ars article): http://dnlongen.blogspot.co.uk/2014/02/breaking-down-asus-router-bug.html

I then did the manual software upgrade on my router, and I was back to my insanely slow speeds (which is weird). All this happened real time, and the speeds triggers in the Bitcoin block download happened the same moment software upgrades happened. From slow to fast and then back to slow after applying the manual patch.

I need to check this on another network for sure, to finally get a full picture of the situation. But it would not surprise me these router attacks affect Bitcoin. Thats what all attacks are about these days, no?