I'm trying to make a bitcoin app and would like to use a full node so I purchased a 128gb usb 3.0 drive to store it on. I use an early 2014 macbook air: 1.4 GHz Intel Core i5, 8 GB 1600 MHz DDR3. Is processing being throttled by the usb connection? Drive is formatted as mac os extended journaled.

Using bitcoin core, it is syncing very slowly. After almost 24 hours it says last received block was generated 2 years 3 weeks ago. The sync bar is about 1/8 of the way done. Any thoughts or recommendations would be helpful.

  • I'd expect disk latency / seek time to be more of a bottleneck than throughput. Verifying the blockchain means lots of random reads and writes to find and update transactions in the database. Something I might try is to make symlinks so that blocks/index/ and chainstate/ are on a ramdisk, and then copy them back to the disk after syncing is complete. Dec 17, 2015 at 1:38
  • Another option is simply that you are limited in downloading the blocks by network bandwidth, or by the responsiveness of your peers. If you look at top or the OSX equivalent, how much time is spent in running and/or iowait? Dec 17, 2015 at 1:40
  • It might help to increase your dbcache option. For example dbcache=400 (I think 100 MB is the default)
    – Jannes
    Dec 17, 2015 at 13:09
  • @jannes, This is what ended up working. I set it to 5000 and it looks like it will finish in a day or two thanks. Dec 17, 2015 at 17:50
  • I'll put it in an answer then instead of a comment. Please accept. Also: you might want to turn it back down a bit after the initial sync has finished. 5GB sounds like a bit overkill.
    – Jannes
    Dec 17, 2015 at 20:10

1 Answer 1


Increasing the database cache should help a lot to reduce disk I/O. For example dbcache=400 (100 MB is the default).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.