I run geth with the arguments below:

geth --fast --cache=1024 --datadir ./.ethereum 

Now the datadir (.ethereum) takes more than 26Gb and the syncing process is continue. Is it OK? Because it looks like it try to download a whole database.

I've found many topics about that fast sync mode should take about 10 Gb of disk space. Maybe it is outdated? Is there anybody who have geth client working in fast sync mode? Could you please check the size of your datadir directory?

Geth version is 1.6.7 Startup logs: https://gist.github.com/ValeryDubrava/23faf1285981b6b37afe8d2c39eeb713

2 Answers 2


Possible, I do not enough patience - it stopped on 39Gb. Now it gets new block only in about 10 sec. So, it looks like current database size in fast mode is 39Gb.

Update: after restart it shows message: "Blockchain not empty, fast sync disabled" (full log: https://gist.github.com/ValeryDubrava/ba7d6b8df0f4e69d223663d8304373a6)

Sync process was fast after restart: 41 blocks was imported immediately. So, it seems that 39Gb is a full sync. And geth has a some kind of bug, which starts full sync if database was not cleaned (of right cleaned).


The size of your blockchain really depends on what type of software you used. You can take a look at size of the blockchain post. The geth --fast command only work when the db is empty (geth removedb to remove the db). If you did a simple synchronization before the geth --fast, the client will continue its simple sync.

I've found many topics about that fast sync mode should take about 10 Gb of disk space

Definitely outdated. I did make a geth fast sync (1 month ago) and it was more like ~ 29 Gb.

Loaded most recent local fast block number=2257422

There is currently (10 August 2017) ~4 100 000 block in the blockchain so your client doesn't seem to be synchronize.

The Parity client is the ethereum client that take the less of space (~10Gb) (it seems) if you want to use less space on your computer go for it.

  • I've never run geth in full mode. More than, geth 1.6+ has fast mode by default. Possible, when I restarted geth (which was not fully synchronized in fast mode) it begun full synchronization? It looks like a bug. Commented Aug 10, 2017 at 7:32
  • No no, you are sync in fast mode. I just answer to your question but in your answer you seem to be correctly sync. Commented Aug 10, 2017 at 7:42
  • How can I check what mode a node is currently running in?
    – rraallvv
    Commented Nov 25, 2018 at 2:19

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