Bitcoin Forum

Lately I have (for the first time ever) been putting some time into syncing the testnet blockchain to practice rawtransaction crafting to set up a cold storage bitcoin core installation into an airgapped linux laptop... whatever, my question is.. who the hell bothers mining a blockchain with fake bitcoins? I mean, it's a real blockchain with real blocks and real transactions right? but the tokens are worthless... so who is maintaining a worthless blockchain?

Also, anyone knows the EXACT testnet current blockchain size? where do I look at this?

Anyone of the block explorers which support TestNet... like blockcypher... https://live.blockcypher.com/btc-testnet/

The difficulty is much lower.

Apparently the highest difficulty in recent months (https://testnet.smartbit.com.au/charts/difficulty) was equivalent to the mainnet in April 2013 (https://www.smartbit.com.au/charts/difficulty?from=all), but usually it's more like 2012, or nothing.

Yes I've already bookmarked this site for when I have my 2 testnet nodes setup ready to test around with raw transactions and see if I do it correctly, but I can't see a graph of the actual blockchain size. Something like this:

https://blockchain.info/en/charts/blocks-size

but for the testnet.

As of right now, it's downloading really fast. Yesterday it was so slow... download speeds is so random with Bitcoin Core for some reason. Yesterday it said "2% hourly increment". Now at current speeds, im making %30 hourly increments, so I will have it downloaded in 2 hours. I guess it depends on how lucky you are to catch a fast node.

Maybe HDD access is the bottleneck? My mainnet sync speed varied by a factor of 10, likely due to Core's inefficient memory caching.

But why would the speed be random due using HDD? according to the network activity, it just stops downloading, there are huge gaps of no activity in the network window, I mean you get these big green lines when it goes fast, then it just stops download, then it begins again, at lower speeds, eventually the speed is so slow that it's maddening so I have to close it and re-open again.

Next time I sync a full blockchain I will use SSD, but like I said... it just has big gaps in between downloading, then download speed decreases.

There are two problems I noticed (but using pruned mode, which may contribute to the first):

HDD I/O is highly unoptimized, and the effect varies. Maybe it changes depending on the random blocks/transactions it's processing at a given time. See more here. (https://bitcointalk.org/index.php?topic=2291857.0) The solution: Use a RAM drive for the chainstate directory, and copy it back to HDD after it's fully synced. Actually, unfortunately, I do this RAM drive nonsense on practically every startup.

Sometimes it stalls without downloading blocks (https://bitcointalk.org/index.php?topic=2511586.msg25671154#msg25671154) for no apparent reason. Possible solution: restart Core.