As the mere size of the constantly changing data file tampers with my backup concept, I would like to ask if there is a way to split this file into many smaller pieces. I have no problem with the size as such, but with the amount of changes.

Background is, I do my backups with rsnapshot. This links files which haven't been changed on the target together, while changed files are copied in full.

That's why I would imagine to split the currently about 763 MB big blk0001.dat into two files:

  • blk0001.dat having maybe 700 MB, and not changing (frequently) in the future.
  • blk0002.dat holding the rest.

As the 2nd file grows steadily, I would, after it has reached a certain size, put more data from it into blk0001.dat, and eventually stop changing this file at all, starting a 3rd one.

Has someone done this already?

  • 3
    Just in case you're unaware, backing up your bitcoins only requires wallet.dat, not the block chain data. Commented Nov 21, 2011 at 14:07
  • 1
    Yes, but I don't want to download all that stuff in a case of emergency... that needed me 2 days or so the last time...
    – glglgl
    Commented Nov 21, 2011 at 14:38
  • OTOH: as I have it on 3 computers, I exclude it everywhere from the backup. Good point!
    – glglgl
    Commented Nov 21, 2011 at 14:39
  • @glglgl You can always use e-wallets if you really want the emergency access time - en.bitcoin.it/wiki/Category:EWallets
    – ThePiachu
    Commented Nov 21, 2011 at 22:50
  • Backing up my wallet is no problem. I am just worried about the huge files. But if I just exclude them from backup, all is fine.
    – glglgl
    Commented Nov 22, 2011 at 8:58

3 Answers 3


If you want custom file handling, you'll need to alter the client code, or write some application that would be reading from the dat file and splitting it accordingly. I haven't heard of any existing offline solutions for alternative handling of the files.


This is actually already implemented: blk0001.dat contains the first two gigabytes of blockchain data, blk0002.dat contains the second two gigabytes, and so on. We just haven't hit two gigabytes of data yet.

  • one gigabyte is much stuff...
    – glglgl
    Commented Nov 22, 2011 at 17:49
  • 1
    @glglgl You can request a feature for the Main Client to offer variable size of .dat dumps here: github.com/bitcoin/bitcoin , although I don't think it will be a high priority, unless it turns out that a lot of other people want the same.
    – ThePiachu
    Commented Nov 22, 2011 at 21:34

From https://github.com/bitcoin/bitcoin/issues/1400#issuecomment-6028443, Gregory Maxwell explains that blk0001.dat will contain closer to 2GB of blockchain data. He also explained that a gambling site and a miner with an inefficient payout system are responsible for the fast increase in file size.

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