Topic: Me panicing because of a Core crash. Now I have to redownload the chain. Lame. (Read 3731 times)

Before you try anything else find you wallet.dat file and make a backup copy of it. The file is most likely in one of these locations: https://en.bitcoin.it/wiki/Data_directory

Next step: Have you tried clicking "yes" when that box pops up? What happened?

hello sorry for the intrusion but my laptop shutdown unexpectedly whilst my bitcoin core was still in synchronisation and i was 2years 13 weeks gone.Problem is anytime i try running the app it shows me "error loading block database,do you want to rebuild the block database".
How do i proceed as i have already received coins which i have in two separate addresses and can not afford to lose this coins.
please users i need your advice.

okay good now do yourself a favor back up your wallet.  and maybe open a smaller account with an online wallet use 1 or 2 of them with 1 or 2 coins. 

Solved.
I did indeed still have all my coins.
The system just moved wallet addresses randomly for no reason making it look stolen.

Good Advice.
I have switched to SSD again.  I wanted it on an external I could just leave offline.  I will need a SSD external next.
This reindexing crashed on me 2 days into it, so I had to start over again.
The BTC Core is not even using 100% CPU, mostly just 36%.  So it is not even taking advantage of the CPU, and only using less than 350MB ram when I have 16GB.  Very frustrating.

Yes I should put my eggs in different baskets.
Money Management basics.

ssd's are one  way.  but not this time.  the slower rebuild is the best way to go.



like it or not you have enough coins (48)  

 to consider a few pc's  that mainly hold your coins and do nothing else.  48 coins is close to  14,500 usd.

 A pc with just bitcore  will speed thing up…    I have a pc with  an older quad core 16gb ram and a 250 gb ssd .

It can do a reindex in under 10 hours.

You could  consider having   2 wallets with blockchain.info   one with 2 or less coins  one with 4 to 8 coins.

and then the rest of the coins in a safe wallet.

Fortunately I did not delete the block files, all 46.8GB and growing.
Perhaps the BTC network data passing through my system is new stuff and not part of the reprocessing of all blocks.
My CPU has an average of 88% CPU idle.  I have a quad core MBP with 16GB Ram, my CPU is not slow.
BTC Core is using under 350MB of Ram... and an average of 40% CPU.  Not using much.
My bandwidth at home is 120 MB/s up and down. 

How can I speed this up if it is all CPU, it should be done quickly.

Some command line settings I should try?

For a computer, that is jumping around. It is not in order that it is reading the file in. In order to go back to a confirmed transaction, it first needs to get through the corrupted data, which it will have no idea what that data is, before it can reach any good data. Even so, depending on what it was reading, it may be corrupted in multiple places in the database. The corruption might also might not be of the transactions, but of the file and database structure itself. If that was corrupted (which is probably the case since bad transactions can just be redownloaded) then having good transactions means nothing as it cannot read them or understand the format of the data. Just to be safe, it will reindex. Reindexing guarantees that the data it reads is not corrupted. Otherwise, the data might be corrupted and such a corruption can negatively affect the entire program.

Reindexing does not mean it is downloading. It might appear that way, but it is in fact reading the data off of the blk files and indexing them into a database in ldb files. If you were stupid enough to delete the blk files then it will be redownloading. Even so, it isn't the bandwidth of Bitcoin's network, it is your own internet bandwidth that limits the download. The bottleneck for you right now is your CPU and RAM. Reindexing is all on the CPU and the RAM. If you don't have a good CPU and enough RAM, then it will take a long time. For me, I can have a reindex done in about 15 hours. Some people have them done in 1 or 2 hours, others a few days. But the problem is on your computer, not the network.

I wouldn't even call this jumping around.  I would call it going back to a confirmed transaction and looking for the error after that point.  The next version would hopefully be backwards compatible, read the current DB/chain on the system and write it locally into the new format, so that it does not need to redownload. 

The download is the problem.  6 days, because the bandwidth of bitcoin's network is so slow.
So I cant buy anything for 5 more days.  =(

Still better than those mother fuckers at paypal that do chargebacks 25 days after the fact.

Well the linear stuff is not just the database, but computers in general. They can't just jump around and process multiple things in different orders like humans do. What Bitcoin Core can do is migrate to a more ACID (Atomicity, Consistency, Isolation, Durability) database. That would allow it to recover better from crashes and not have to reindex every time the database corrupts. The only problem is that changing databases would require a huge rewrite of the code to support a different database and then that new version would most certainly not be backwards compatible. It would have to reindex the first time.

wow ok.  Sounds like nobody thought it would get this big.
They need to make the next version use a better database system that is not linearly.
Simple fix then to a very big problem.

It doesn't spam and fatten up the chain, and it is still technically in alpha.

Bitcoin is in alpha development still. That is why version 1.0 still doesn't exist. It isn't stable and ready for mainstream adoption yet, which is why it is still labeled alpha by the core developers.

Nope, it doesn't spam the blockchain with more crap. It doesn't make a difference to that at all. The reason for using different addresses for everything is for security. It makes it more difficult for people to track your payments to places and it makes it easier for you to track payments to you. Also, by using multiple addresses, it is more difficult for people to know how much Bitcoin you actually have.

It can't because LevelDB (the database type used by Bitcoin Core) is not all that great with recovery. Once it corrupts, the data may still be readable, but parts of it won't be, and it does not know where. The corruption would not only be just at the end where the latest transactions are, but could be throughout depending on what was open at the time. The corruption also prevents Bitcoin Core from being able to open and read the database as it should. While humans can open the file and read it(with the right tools), the computer is not able to interpret the data since it comes linearly. Humans can jump around and look at the data to find stuff that we need, but the computer processes things linearly. If it receives data it doesn't recognize, then it will crash and error out. The corruption causes this erroring and it can't be fixed without rebuilding the whole database.

Since the data is read linearly, it won't ever be able to get to the point where it can read good data. Due to the corruption, it will error out and take the safe route of having to reindex the whole thing.

This is sad that BTC is so unstable that you can't just use one address.  It spams and fattens up the chain for no reason, making it slower to download every time someone has a crash.  Very bad for BTC to have this problem.  No wonder the mainstream will not adopt this broken tech.  It's like in BETA forever.

I have this problem a lot. Do not use the same addresses over and over. This will prevent crashes like the many ones I have experienced. I am sure glad I was wise enough to create a backup.

Ok, well now I cannot buy anything for a week now that the blockchain is redownloading the entire thing because of one little crash.
Glad the money is hopefully still mine.
But I cant use it now.
One day the blockcain will be so large that any crash may take a month to download.
I have very fast internet, but the blockchain data is a very slow download.

yeah, that is a change address.

The private key of the wallet you made that payment is the one which controls this new address with the bitcoins.

Ok Thank you guys!
I was in a panic and very unhappy.
I do have a backup.
I did create a new wallet and moved BTC, then backed up wallet.dat.

The fact that I spent money after the 18th was comforting because I knew I wasnt really broke on that day.
This is the first time my only receiving address shows as empty, and as if it had forwarded the BTC elsewhere for no reason.


Why is it better to use a different address every time?  Doesnt that just spam the blockchain with more crap data and collectively result in making it take a week to download because everyone thinks they need to keep making up new BTC addresses for each transaction?

Thanks.
I will try a rescan, but it wants to redownload the "chainstate" folder.
I am not sure if it is possible to rescan that, if the core deleted it to rewrite it.
Wallet file is still here, and I did make a backup, encrypted and put someplace else.

I hate that the BTC Core is so stupid it has to rewrite perfectly good data just because one small part went bad with the BTC crash.  It cant just find and rewrite that one part, or go back one day or at least back to the day of the most recent transaction when everything must have been ok, and start from that time, it has to go back to day 1!  wtf. 

BTC Core needs to assume the date of the last confirmed transaction was good, and only go back to that date.  Not back 6+ years. 

I have had a similar situation.If you have a back up, do not panic.Relax 

Your coins are still there, like explained above.

Now that you got a good scare time to learn how to backup and don't have a lot of coins in your wallet in your desktop, you should distribute those coins between a few addresses.