Copying instead of downloading the blockchain

[RangerK]

In the interested of saving time, I tried this recently (on Ubuntu 12.04) and the qt client kept hanging without ever opening.  Am I correct to assume that the blockchain can only be downloaded, not copied?

[bit_kevin]

You can use bootstrap.dat when first start an bitcoind.

FYI:
https://bitcointalk.org/index.php?topic=117982.0
http://eu2.bitcoincharts.com/blockchain/

[kjj]

It is possible to copy the blockchain around.  At least it was pre-0.8.  I don't see any reason why you wouldn't be able to after leveldb, I just haven't tried it yet.

You just need to make sure that you get the entire chain and index in one shot.  In the BDB days, that meant doing a shutdown-with-detach, then copying all of the block files with the index.

[juhakall]

I copied all my *coin blockchains from Debian Linux to FreeBSD. All clients were properly shut down on Linux. None of the newly compiled clients would work on FreeBSD because of database errors, until I removed the copied blockchains and started from scratch. Should the blockchain files be transferable between different operating systems? Can anyone explain why I had to do this?

[kjj]

I transferred all my *coin clients, including their databases, from Debian Linux to FreeBSD. They were all properly shut down. None of them would work until I removed the databases and started from scratch. Should the database files be transferable between different operating systems?

I have no idea.  It would depend on how the database library is written.  The blockchain files themselves are platform-agnostic: values are written in a screwy byte order and each client is responsible for converting that order to their internal format.

If I had to guess, I'd expect the database files to be similar, and thus be compatible between operating systems, and maybe even between CPUs.  But I don't really know.

When you say they were shut down properly, do you mean the databases were detached too?  Do the altcoins even support that correctly?

[RangerK]

I copied all my *coin blockchains from Debian Linux to FreeBSD. All clients were properly shut down on Linux. None of the newly compiled clients would work on FreeBSD because of database errors, until I removed the copied blockchains and started from scratch. Should the blockchain files be transferable between different operating systems? Can anyone explain why I had to do this?

Interestingly, I also tried a move between operating systems.  (Windows XP -> Xubuntu).  Haven't experimented copies within the same OS.