Ethash folder and small SSDs

Hello fellow miners, minters & other altcoiners, a quick note to help with Ethereum mining today.

If you’ve been mining Ξthereum you might have noticed a folder a folder named Ethash in your User profile on Windows.  I found out about it when trying to migrate my HTPC to Windows 10 on a 60 gig SSD and discovered this ersatz 10 gig folder. It contains an up-to-date DAG that the miner needs for optimal performance but 8-10 gigs is quite a lot of space for such a small drive.

By the way, if you don’ t know what Ξthereum is but you did find the folder on your machine, good news!  Someone has been making money using your computer!  Bad news is, it isn’t you.  Maybe someone it’s someone you know, or it could be a virus, either way you should investigate; such a virus can end up costing you a lot in electricity and wear out your hardware.

The usual Ethereum miners don’t have a parameter to set the ethash path, but there two simple workarounds to lighten the load on your small SSD.

  1. Use no-precompute when starting your miner so there are no file saved.  The drawback is that you’ll have to recompute a new DAG every time you restart your miner or after a transition to a new DAG.
  2. Create a hardlink to a larger drive.  I don’t think there’s any noticeable performance hit with using a HDD for this. It could even be a spare old SD card or flash drive, but using those might conceivably add a second of delay to each block mined due to the slower interface.  On Windows, stop your miner, delete your ethash folder (there’s no risk involved) and create a hardlink by starting a command shell as administrator and type
mklink /J c:\user\username\appdata\local\ethash f:\ethminer\ethash

or appropriate folder paths.  Problem solved!

Ok it’s a pretty obvious trick but I hope it helps someone out there.

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